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Glossary of MinSE


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A

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Vapourization or sublimation of a solid surface. Usually achieved by irradiating a solid surface with a high power density laser, plasma or electron beam.
Hungary flag Szumblimáció
Keyword(s):
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Material loss (wear) of a surface due to micro-scale cutting/shearing by impinging high hardness particles or grit. Also see three body wear and erosive wear.

Hungary flag Kopás
Keyword(s):
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Wear taking place by the mechanism of abrasion. A process which involves hard, fine particles, cutting through or ploughing over a relatively ductile bearing surface during sliding contact, thereby removing material from the surface (diagram). The abrasive particles maybe suspended in a fluid. Also see three-body wear.
Abrasive wear
Abrasive wear

Hungary flag Kopási elhasználódás
Keyword(s):
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A mechanism of wear involving localised welding together of micro-aperities during sliding contact, as for example between two bearing surfaces; such micro-seized contacts subsequently fail through micro-shearing or tearing causing the removal of surface material (wear). Debris particles can range in size from a few hundred microns to significantly less than one micron. A rigorous mechanical model of the interaction between a rigid and ductile asperity has recently been advanced by B. S. Hockenhull, E. M. Kopalinsky and P. L. B. Oxley (J.Phys. D: Appl. Phys., 1992, 25, A266-A272). Eventually this may be developed further to consider the more complex situation of the interaction between asperities with similar plastic properties. Some tribologists now regard the term "adhesive wear" to be redundant, yet it persists within the general engineering community.


Adhesive wear

Adhesive wear

Hungary flag Adhéziós kopás

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Designed for measuring shot peening intensity. A standard sample, namely a flat piece of steel, is clamped to a solid block and exposed to the action of a stream of shot. The extent of curvature, after removing the sample from the block, serves as a basis for measuring the peening intensity. Peening intensity is influenced by the velocity, angle of impingement, hardness, size and mass of the shot pellets.

Hungary flag Almen teszt

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Thermochemical treatment involving the enrichment of a metallic surface with aluminium in order to form layers enriched in metal-aluminide compounds. The process is mainly applied to nickel alloys and steels in order to increase their resistance to corrosion, oxidation and erosion. Aluminising can be subdivided into pack aluminising, hot dip aluminising , salt bath aluminising and gaseous aluminising. Pack aluminising has been widely used for the oxidation protection of nickel base super alloys used in aero-engines; of crucial importance here is the diffusional formation of the intermetallic compound NiAl. Like many other pack cementation methods the pack comprises a source (Aluminium powder), an activator (NH4Cl) and a diluent (Al2O3). One typical composition comprises (by weight) 15% Al (325 mesh), 3% NH4Cl and 82% granular (120 mesh) Al2O3. It is essential to flood the pack with argon during pack aluminising, which for nickel base alloys is carried out ≈ 1090°C for 8 to 10 hours. Steels can be aluminized in the temperature range of 850-1050°C for 2 to 6 hours. If the mixture is tumbled shorter times often suffice. Diffusion layers maybe up to 100 µm thick. A secondary heat treatment can be carried out at 815 to 980°C for 12 to 48 hours in a neutral atmosphere. This improves the toughness of the aluminised layer and increases its depth (up to ≈150 µm). The aluminising of austenitic stainless steels probably warrants further investigation. Apart from producing a hardened surface through the formation of metal-aluminides and aluminium oxide, aluminised austenitic stainless steels have the ability to act as hydrogen diffusion barriers. In this regard they show potential for use in fusion reactors. In the case of nickel alloys, pack aluminising technology is now being superseded to some extent by the increased use of NiCrAlY, CoCrAlY and other oxidation resistant coatings applied by thermal spray techniques, such as plasma spraying.

Hungary flag Alitálás

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The process of transforming a metallic or non-metallic material from the crystalline state into the amorphous or glassy state. Commonly in surface engineering, a surface is melted with a laser beam (using power densities ≈ 105 to 107 W/cm2 with interaction times ≈ 10-3 to 10-7 seconds) and rapidly solidified at cooling rates exceeding 105 K/s thereby suppressing the nucleation and crystallisation processes; this technique is termed laser glazing. Alternatively, materials (especially carbon and ceramic compounds) can be deposited as amorphous coatings (e.g..via sputter deposition), if the substrate is kept at temperatures well below 100°C.

Hungary flag Amorfizálás (üvegesedés)

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An atomic structure lacking long range order or periodicity; characteristic of SiO2 based glasses and other glassy solids. When irradiated by monochromatic X-rays such materials produce a characteristic broad peak spanning several degrees of 2q, where q is the Bragg angle.
Hungary flag Amorf szerkezet
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A machine designed by the Swiss Company Amsler that enables two test wheels to run against each other with varying degrees of traction. Typically, the upper wheel is rotated at 10% of the peripheral speed of the lower wheel, although, many other configurations are possible. The test can be run lubricated or dry. The test was designed to emulate the contact stresses developed at the contact surfaces of gears. It has therefore proven useful in the optimisation of carburised and nitrided steels intended for use in gearing applications. Normal forces of up to 2000 N can be readily applied.
Amsler test
Amsler test
Hungary flag Amsler kopás teszt
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A negatively charged ion that migrates towards the anode during electroplating or any dc plasma process.
Hungary flag Anion
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A treatment mainly applied to aluminium, magnesium and titanium alloys, whereby the natural passive surface oxide of these materials is thickened considerably by a process of anodic oxidation conducted in several proprietry electrolytic solutions. The oxide layers offer some durability against wear and corrosion and can be coloured by dyes for aesthetic appeal. One of the highest volume products is extruded aluminium forms used in window frames and other architectural applications. In recent years anodising has been exploited as a means of producing alumina based membranes for use in separation of gaseous mixtures used in the chemical processing industries.
Hungary flag Eloxálás
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antifriction coatingAny coating that can be applied, especially to bearing surfaces, for the reduction of sliding friction and wear. Traditional metallic coatings used in lubricated bearing systems include lead, indium, silver and tin alloys. For dry lubrication systems, such as those used in satellite mechanisms (durability in outer space), ceramic coatings like TiC have found favour. Other low friction ceramic coatings, like TiN, ZrO2 and Al2O3, are being evaluated for the bearing surfaces of artificial hip and knee joints.
Hungary flag Súrolódásmentes bevonat
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Sometimes designated ALE. A comparatively new technique. The first experimental investigations were made in 1974 by Suntola and Antson, while the first industrial evaluation was made by the Lohja Corporation (Finland) in respect to the deposition of ZnS for use as electroluminescent displays. Other materials that are deposited include CdTe, GaAs, GaP, Ta2O5, and ZnSe. ALE seeks to deposit uniform, defect free layers of material that are only a few atomic layers in thickness onto oxide based substrates used for solid state electronic devices. The constituents of the coating are reacted precisely at the surface and become attached and formed through a repititive cycle of chemisorbtion and desorbtion; in the example of ZnS sequential atomic layers of Zn and S are alternately built up. For further details consult the review of Simpson et al, Surface Engineering, 3, No4, 1987, pp 343-348.
Hungary flag Atomos réteg-epitaxia
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A term invoked by Trent to explain the wear of cemented carbide tools, whereby singular grains or groups of grains become torn or "plucked" from the tool contact faces during metal cutting. Attrition wear is especially prevalent at relatively low cutting speeds when the metal chip forms a seized deposit around the tool cutting edge, termed a "built-up-edge", which periodically breaks away from the tool, and takes with it fragments of tool material. Hence, the chip-tool contact is of an intermittent nature. Even at higher cutting speeds, where the built-up-edge no longer forms, attrition wear can take place on the flank faces of cemented carbide tools, especially those containing high volume fractions of (W,Ti,Ta,Nb)C phase or having a relatively coarse WC grain size (≈3-5 µm). For further details see E. M. Trent: 'Metal Cutting', 3rd ed; 1992, London, Butterworths.
Hungary flag Kopás
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An electron spectroscopy method useful for obtaining chemical compositonal information of the outermost 10 atomic layers or so of a surface. The technique is carried out under ultra-high vacuum conditions (≈10-9 torr), and uses a low power density electron beam to "probe" the sample surface. During irradiation by the beam, characteristic auger electrons are emitted by the sample. Depth profiling can be achieved by the conjoint action of an ion beam gun, which directs argon ions at the sample surface and strips the sample surface of, for example, the natural external passive layer. The sample must be electrically conducting to assure satisfactory coupling by the electron beam. Hence, the method does not lend itself to the interrogation of ionic or covalently bonded ceramic surfaces (since they are non-conducting).
Hungary flag Auger elektron spektroszkópos módszer

B

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One type of source deployed in magnetron sputter deposition. The balanced magnetron is a standard magnetron sputter cathode in which the outer magnetic field is balanced to match that of the inner field. Until the mid-late 1980's all magnetron cathodes were of this design. The term has been invoked to differentiate this type of magnetron from the more recently developed unbalanced magnetron. Balanced magnetrons are still widely used for coating semi-conductor devices but are less popular for the deposition of tribological coatings, since the substrate current density is low and auxiliary hating is needed to assure adequate coating adherence. Also see unbalanced magnetron.

Hungary flag Kiegyensúlyozott magnetron

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A controlled polishing technique enabling the ready measurement of coating thickness; especially for thin (≈ 1-10µm) ceramic coatings. A hardened steel or cemented carbide ball, ≈ 20 to 50 mm diameter, is coated with 1µm diamond paste and rotated on the coated surface until the coating is worn through. Since the diameter of the ball is known, a taper section of known geometry is obtained. The width of the wear scar is easily measured with a light-optical microscope and the coating thickness calculated. The method gives good results for coatings that are 1 µm thick or greater.

Hungary flag Kráterképződéses teszt

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The father of modern surface engineering who pioneered the exploitation of glow discharge plasmas for plasma nitriding and sputter deposition. His patents, originating during the 1930's and continuing through to the 1960's can be regarded as truly seminal. He was born of German parents in Amsterdam on 31st July 1896 and died in Zurich on 30th December 1966. Much of his early life was spent in Munster, N.R.W., Germany. He subsequently established a small research and development company called Gesellschaft zur Forderung der Glimmentladungsforschung whose sole goal was to achieve the industrial exploitation of plasma assisted techniques. Further impetus was provided by a subsequent collaboration with Ionon of Koln (Cologne) which in turn lead to the foundation of Klockner Ionon who transferred plasma nitriding on a major scale to the European and Norh American manufacturing sectors. In later years many other companies emulated the ideas of Berghaus, and today plasma techniques, especially plasma nitriding, is practised in all technologically advanced countries.

Hungary flag Berghaus, Bernhard

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Hardness determined using a triangular base pyramid diamond indenter. The included angle at the apex of the pyramid is 65°, i.e., the angle between the vertical axis and each of the three faces. The Berkovich indenter is proving popular in nanoindentaion hardness.

Hungary flag Berkovich keménység

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A proprietry gaseous austenitic nitrocarburising treatment.
Hungary flag Beta
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The usual configuration of sputter deposition, whereby a negative bias is applied to the substrate during sputter deposition, the purpose of which is to raise the substrate ion density, causing heating and much improved coating adherence. The chamber walls are held at positive-ground potential. The magnitude of the substrate negative bias depends upon the type of sputter source and the point of time in the coating cycle. At the commencement of the treatment, a large negative bias (≈1000 volts) maybe applied to effect a "clean-up" of the components surfaces, through glow discharge sputtering. At the commencement of sputter deposition, the substrate bias voltage is reduced: (i) for a conventonal balanced magnetron source to ≈500 volts; (ii) for a modern unbalanced source to ≈ 50 - 200 volts. Also see balanced magnetron and unbalanced magnetron.
Hungary flag
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(i) The main component of a polymeric coating material, which binds the pigment and filler particles together and creates a durable bond with the substrate. Also known as a film former. (ii) The metallic Co phase in WC-Co spray deposited coatings.
Hungary flag Kötőanyag
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A surface finishing process leading to the formation of a thin black oxide film on the surface of a metallic object, performed with the aim of improving corrosion resistance, usually for decorative applications. Steel objects are most frequently blackened in an oxidizing bath or furnace.
Hungary flag Feketedés
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A technique of non-eqilibrium carburising to enable rapid carbon transfer. See vacuum carburising and plasma carburising.
Hungary flag Gyors-diffúz kör
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This thermochemical treatment involves diffusing interstitial boron into (mainly) steel or cemented carbide components at a temperature such that highly durable surface mono- or multi-layers of transition metal borides are formed through a reaction between the boron and one or more metals in the substrate. For steels, treatment temperatures are in the range of 750 to 1050°C; for cemented carbides temperatures are ≈1000°C. Other substrates, like titanium and nickel base alloys can be treated in principle but industrial boriding of these alloys is comparatively rare. Various boriding media are available: plasma, gas, salt bath (electroless and electrolytic), pack and paste. Salt bath media are mainly exploited in Eastern Europe; their negative environmental draw backs has prevented wider exploitation in Western Europe, North America and Japan. The main-stay technique outside Eastern Europe remains the pack process, despite notable development efforts in gaseous and plasma boronizing. A common pack comprises (by weight) 90% SiC, 5% B4C and 5% KBF4. The SiC acts as a diluent, the B4C acts as the principal boron source while the KBF4 serves as an activating and fluxing agent. The latter can be satisfactorily replaced by NH4Cl. Boriding has the ability to convey improvements in wear resistance while simultaneously imparting resistance to corrosion by mineral acids and molten metals (especially zinc and aluminium). Boride layers produced through boriding tend to lack the toughness required for high contact loads especially those delivered at high strain rates; in this regard they are inferior to nitrided or carburised steels. The duplex FeB/Fe2B produced on boriding steels, under moderate boron potential, results in the creation of detrimental residual elastic stresses in the vicinity of the FeB/Fe2B interface. This is one factor that is responsible for the observed brittleness of borided surfaces. In the case of plain carbon and low alloy steels, boride layer toughness can be improved by boriding under low boron potential to produce a mono-phased layer of Fe2B. Another possibility is to conduct a post boriding annealing treatment ≈850°C, in vacuo, thereby converting the duplex FeB/Fe2B into a mono-phased Fe2B layer. The latter option is obviously less economic.
Hungary flag Boridálás
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See gaseous carburising
Hungary flag Boudouard reakció
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Any lubricant that serves to enable stable boundary lubrication. If the lubricant fails, seizure will result. Boundary lubricants are often added to oils as "additives". Various types exist, which include hexadecanol, oleic acid amide and stearic acid.
Hungary flag Határ kenőanyag
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A condition taking place in lubricated machine components where two sliding bearing surfaces pass over each other but are prevented from making metal on metal contact by a very thin boundary film of organic lubricant. It is argued that the film may only be a few molecules or even one molecule thick. This condition only arises under very high contact pressures or when sliding speeds are low. An example of this is the die-workpiece interface in wire drawing.
Hungary flag Határ kenés
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A bainite-like decomposition product of Fe-N austenite, induced by appropriate isothermal cooling, after austenitic nitriding.
Hungary flag Braunit
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A ball of WC-Co is pressed by a heavy load (often 3,000 kg) into the surface of a metal and the diameter of the depression is measured. The Brinell Hardness Number (BHN) is the ratio of the load (kg) to surface area (mm2) of the indentation, hencethe units are actually in kg/mm2. Both macro and microindentation versions exist. The technique is widely used in the steel heat treatment sector. Named after J. A. Brinell (1849-1925).
Hungary flag Brinell keménység
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A surface finishing operation performed for producing a smooth, reflective, surface by bringing it into contact with a revolving soft-fibre wheel charged with a suitable compound consisting, typically, of a fine abrasive immersed in a binder.
Hungary flag Polírozás
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A mechanical surface finishing operation applied to metallic objects. The surface is subjected to a micro-hammering action by one or more hardened polished steel tools making a rotary or reciprocating motion. The main purpose of burnishing is to rapidly obtain a very smooth surface. It work-hardens the surface and increases the fatigue strength of the component. Burnishing may inadvertently happen during surface grinding if the selected operational parameters are too severe for the material being ground.
Hungary flag Tükör polírozás

C

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When carburising steel, it is the ratio of the vapour pressure of carbon in austenite to the vapour pressure of graphite (the reference state) for any given temperature.
Hungary flag Karbon reakcióképesség
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A laser in which the active medium comprises a mixture of 10% CO2 , 30% N2 and 60% He. CO2 laser light haa a wavelength of 10.6 µm. For laser alloying and transformation hardening, carbon dioxide lasers are typically rated in the range of 1 to 3 kW and can deliver a maximum power denisty ≈106 to 109 W/cm2 to the surface. For further information see LASER.
Hungary flag Széndioxid (CO2) lézer
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The amount of nascent carbon available at the surface for solution in austenite during carburising. Often expressed in wt-% in relation to the Fe-C system. Depending on the media employed, the carbon may or may not be in equilibrium with the surface. Measures of carbon potential can be gained from dew point determination, infra-red gas analysis or oxygen sensing. Also see gas carburising, infra-red gas analysis and zirconium oxygen sensor.
Hungary flag Karbonpotenciál
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Carbon concentration as a function of depth below the surface.
Hungary flag Karbon eloszlás
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Thermochemical diffusion treatment involving the enrichment of a surface with carbon. It is mostly applied to low carbon (0.12-0.18 wt-%) steels, but non-ferrous metals, like titanium can also be hardened through carburising, but the mechanism of hardening in that example is quite different. Nowadays, carburising is mostly carried out using gaseous, fluidized bed or plasma media, although in some technologically less developed countries, salt bath, paste and pack methods are still widely used. This comment is reserved in part for large volume industrial operations and excludes small workshops and other engineering businesses where pack carburising is frequently justifiable given their very small turnover of work; in such cases, investment in major capital equipment is clearly unjustified. Steels are generally carburised between 850 and 1050°C, whilst in the austenitic state; this stage is followed by an oil or gas quench (to ambient temperature) which causes the formation of martensite. Subsequently, the carburised steels are tempered at approximately 150 to 200°C, to obviate case embrittlement. The carbon content of the steel core is sufficiently low (0.12-0.18wt-%C) to retain relatively high toughness, even in the as-quenched state. Specified case depths vary depending upon the application loading, but are generally deeper than those attained by nitriding, reaching a maximum of approximately 2mm. Carburising, like nitriding, improves rolling contact fatigue endurance since the volume expansion accompanying the hardening step, places the carburised case in a state of residual compressive stress. The majority of drive shafts and gears used in automobiles are carburised. It is probably the singular most important surface engineering technology used in the automotive vehicle sector. See gaseous carburising, pack carburising, plasma carburising, salt bath carburising and vacuum carburising. With regard to process control, it is very important to achieve the correct carbon content in the carburised case (≈0.8 wt-%) otherwise excessive retained austenite will result. See retained austenite.
Hungary flag Cementálás/karbonizálás
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The surface zone that has received a change in alloying content after a given thermochemical diffusion method, such as nitriding or carburising.
Hungary flag Réteg
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Strictly speaking this is the depth of diffusional penetration by, for example, carbon after carburising or nitrogen after nitriding. However, within the heat treatment sector, a number of definitions of case depth have emerged; some have become formalised by appropriate standards authorities, like ASTM, DIN and SIS. In the USA, case depth is frequently defined as that portion of the treated zone which has a hardness above 50 Rockwell C. The most precise measurements employ the microhardness technique with Vickers or Knoop diamond indenters. In this instance, case depth is frequently defined as the depth of case with a hardness that is at least 50 kg/mm2 above that of the core.
Hungary flag Réteg mélység
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A general term meaning carburising, carbonitriding or induction hardening.
Hungary flag Kéregedzés
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The erosion of a surface caused by the collapse of vacuum bubbles formed in a fluid. A condition which frequently affects ship propellers and impellers.
Hungary flag Kimaródás
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(i) An obsolete term denoting carburising; (ii) A general term used to denote any surface diffusion method that results in the formation of a surface layer containing interstitial or intermetallic ccompounds. See diffusion coating and diffusion metallizing.
Hungary flag Cementálás
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Polishing of a metallic surface by immersion in a bath containing oxidizing substances which levels and brightens the surface by preferentially dissolving projecting surface irregularities.
Hungary flag Kémiai polírozás
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Less commonly termed chemical vapour plating, thermochemical plating or gas plating. A reactive gas phase deposition process in which one of the reactants (typically a metal halide) is in the vapour state, prior to admittance into the reaction chamber. (Note: a vapour differs from a gas in that it can be condensed by the application of an external pressure. Conversely a gas, being above its critical vapour pressure, cannot be condensed in the same way.) CVD can be carried out at atmospheric or sub-atmospheric pressures. For the production of carbide and nitride ceramics, reactions are of the general form:-
MClx + H2 + N2 ---> MN + xHCl
The kinetics of reduction of metal halides like TiCl4 mean that the CVD of TiC, TiN, Ti(C,N) and Al2O3 requires temperatures ≈1000°C at atmosphreic (760 torr) or sub-atmospheric pressure (≈50 torr). However, by ionising the reactive gases in a radio frequency (RF) glow discharge, the kinetics of reaction can be accelerated to enable deposition at substrate temperatures ≈500-600°C.
flag Kémiai gőzöléses fémbevonatolás
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Micro-fracturing or breaking away of fragments of a brittle coat especially at an edge or a corner.
flag Kémiai adszorpció
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Micro-fracturing or breaking away of fragments of a brittle coat especially at an edge or a corner.
flag Forgácsképződés
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Thermochemical diffusion treatment involving the enrichment of plain carbon steel surfaces with chromium, to impart corrosion and wear resistance. Chromising is generally carried out between 850 and 1050°C for durations up to 12 hours, which produces chromised layers ranging in thickness from ≈10 to 150µm. The constitution of the chromised surface layer depends upon the carbon content of the steel. For steels with 0.3 wt-% C, the chromised layer is essentially ferritic (the chromium remains in solution). Steels containing 0.4 wt-% C show evidence of intergranular carbide precipitation, while steels with higher carbon contents exhibit layers enriched in massive carbide deposits of the same type, i.e., (Fe,Cr)7C3 and (Fe,Cr)23C6. The Vickers microhardness of chromised steel surfaces increase linearly from ≈600 to 1800 kg/mm2 for steels with carbon contents ranging from 0.2 to 0.8 wt-%. The higher the carbon content of a steel, the thinner the chromised layer thickness (for a given chromising temperature and time). Chromising can be conducted using various media. See pack chromising and gaseous chromising.
flag Krómozás
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An electroplating process in which chromium is deposited from a chromic acid solution in the presence of silicofluoride and/or sulphate catalytic anions. Chromium is generally subdivided into 'hard' and 'decorative' plating methods. Hard coatings (2 to 250 µm) are thicker than decorative coatings (<2µm) and are used for engineering application, often in conjunction with a sub-layer of nickel. Various types of hard chromium exist, including microcracked chromium, microporous chromium, porous chromium and crack-free chromium. The latter can only be produced in thicknesses up to 2.5 µm, whereas, the porous or cracked chromium deposits can be up to ≈150 µm. Indeed, it is essential that the microdefective coatings have a minimum thickness ≈80-120 µm in order to confer adequate corrosion resistance. Micro-cracked chromium has a Vickers hardness of 800 to 1000 kg/mm2, while crack-free chromium has a Vickers hardness ≈425 to 700 kg/mm2. There is a lack of hardness data for microporous chromium and porous chromium. The former should not contain less than 15,000 pores per square centimeter; this favours a lateral corrosion path, delaying downward penetration. The formation of micropoorous chromium is achieved by a specialised plating method involving the use of suspended inert particles. Porous chromium plating is, however, developed by an etching procedure after electrodeposition of the chromium; this coating has a coarser distribution of pores. These are designed to retain lubricant, in sliding and bearing type applications. Chromium itself is a base metal; it is the external chromium oxide layer which provides the observed tolerance to atmospheric corrosion. For an excellent review see J. K. Dennis and T. E. Such: 'Nickel and Chromium Plating', 3rd ed; 1993, Cambridge, Woodhead Publishing.
flag Krómozás
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Most commonly achieved by roll bonding two dissimilar metals together above their recrystallisation temperature (hot working), e.g., austenitic stainless steel can be clad to mild steel, producing corrosion resistant steel sheet at a fraction of the cost of solid stainless steel.
flag Plattírozás
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(i) - verb - The action of creating a coating, e.g., by a plasma torch; (ii) - noun - A surface covering, usually of very different constitution to the substrate, which renders an improvement in corrosion or wear resistance.
flag Bevonatolás
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The chemical compatibility of a coating with respect to its substrate. This quality is essential, particularly for high temperatures service, e.g., for coatings that provide oxidation protection for nickel alloy turbine blades.
flag Bevonat kompatibilitás
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The inherent hardness of a coating. For thin coatings, ≈3-5µm, this is less easy to determine. Theoretical models exist, however, that enable the influence of the substrate to be taken into account. For example see O. Vingsbo, S. Hogmark, B. Jönsson, and A. Ingemarsson, in P.J. Blau and B.R. Lawn (eds): 'Microindentation Techniques in Materials Science and Engineering' 257-271; ASTM STP 889, 1986, Philadelphia, American Society for Testing and Materials. Yet another approach is to use the nanoindentation hardness technique.
flag Bevonat keménység
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The interfacial shear strength along the coating substrate interface. Technically difficult to measure.
flag Bevonati határfelületi nyílószilárdság
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Holes or cavities in a coating, which may or may not be surface connected. Expressed as a volume or area fraction. It can be determined by image analysis of microsections or by density measurement methods (e.g., mercury infiltration).
flag Bevonat porozitás
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The distance between the external coating surface and the coat/substrate interface, usually expressed in µm (10-6m).
flag Bevonat vastagság
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The ratio of the tangential (friction) force (F) to the normal force (W) acting on two sliding or rolling surfaces, i.e., µ = F/W A dimensionless constant which should be inedependent of W (i.e., F is proportional to W; this is the first law of friction) providing both materials are stressed below their yield strength and that seizure does not take place. Because of the different contacting geometries µ can be significantly lower in rolling contact than in sliding contact. Also see Laws of Friction.
flag Surlódási együttható
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Any surface treatment involving two or more sequential thermochemical diffusion steps, e.g., see multi-component boriding.
flag Összetett termokémiai kezelés
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Any coating comprising (i) a mixture of finely dispersed metal and ceramic phases or (ii) a number of overlapping coatings of dissimilar materials that can be likened to an American sandwich. Also see duplex surface engineering.
flag Többrétegű bevonat vagy réteg
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Also called white layer and (less commonly) nitrided layer. Refers to the outermost surface layer of nitrided or nitrocarburised steels comprising g'-Fe4N and/or e-Fe2-3N. Usually this zone should not exceed 10µm in thickness. Nitriding conditions are sometimes adjusted to completely avoid its formation (see bright nitriding). The wear resistant qualities of the e-Fe2-3N phase are exploited in nitrocarburising of plain carbon steels. See Nitrocarburising, Nitrotec and Nitrotec S. Contention still exists concerning the relative wear resistance of g'-Fe4N and e-Fe2-3N. Experience has shown that in examples where both phases coexist, detrimental residual stresses are built-up which contribute to exfoliation of the layer.
flag Összetett réteg
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Variation in concentration of elements as a function of depth below the surface. Various techniques are used to derive such profiles, e.g., SIMS, GDOES and SES. Also see hardness profile.
flag Sűrűség eloszlás
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Also termed galvanic contact plating. A form of electroless plating in which a coating of some metal M is produced on a metal object by immersion in an electrolyte enriched in M. In addition a solid piece of metal M is attached to the object to be coated. The action is galvanic in nature; it is a pre-requisite that M should be relatively more anodic than the metal being coated.
flag Árammentes galvanizálás
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The elastic and plastic stresses developed in a material during point contact loading. For example, the stresses developed in an object during indentation hardness testing. Also see Hertzian stresses.
flag Kontakt feszültség
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The interior part of a metal object that is not directly modified by a diffusion or deposition treatment.
flag Mag
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The hardness of the substrate beneath a coating or diffusion zone. A term commonly used in the heat treatment sector in connection with nitrided or carburised steels.
flag Mag keménység
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The degradation of a conducting surface through electrochemical action.
flag Korrózió
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Fracture failure resulting from the conjoint action of cyclic surface stresses and a corrosive environment.
flag Korróziós kifáradás
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Usually referring to the metallic reaction product resulting from a corrosion reaction, although equally applicable to ions or gases produced in the same way.
flag Rozsda
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The rate of progress of corrosion, often expressed as the rate of penetration, e.g., mm/year or as a weight loss per unit area per unit time, mg. dm-2 day-1
flag Korrózis arány
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The resistance of any surface to atmospheric or aqueous corrosion, i.e., resistance to degradation through electrochemical action.
flag Korrózióval szemben ellenállóképesség
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Wear taking place in a corrosive environment. The wear processes could involve abrasion or erosion or other mechanisms. Localised cold-working of the surface, e.g., caused during abrasion, renders the surface more prone to corrosion. Marine engine and food processing components are application sectors where corrosion-wear plays an important role in determining component servicability. The magnitude of the "rest" and "active" component cycles are of particular significance in this regard.
flag Korróziós kopás
:
See chemical vapour deposition.
flag CVD

D

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Loss of carbon from a steel surface to a level well below that of the core, often as the result of prolonged high temperature exposure in an oxidising atmosphere.
Hungary flag dekarbonizáció
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Any coating primarily produced to enhance its appearance. For example see gilding.
Hungary flag Dekorációs bevonatolás
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Any methods that achieve the removal of organic compounds, such as grease or oil, from the surface of an object, e.g., see vapour degreasing.

Hungary flag zsírtalanítás

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A synonym for coating (noun), but also referring to any adherent surface solid formed, for example, as a result of wear or corrosion.

Hungary flag fémbevonat

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The act of laying down a metallic or non-metallic layer onto a substrate.   There ae numerous deposition techniques; these include electrodeposition, plasma spraying, PVD and CVD.

Hungary flag Galván úton bevonatol

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Any process used for the purpose of removing the scale from heavily oxidised metal.  This can be achieved by mechanical (abrasive blasting, tumbling, brushing) or chemical means (alkaline descaling, acid descaling (pickling) or salt bath descaling).

Hungary flag revétlenítés

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An engineered surface with optimal constitution, treatment depth and properties, designed with intent for specific application(s).

Hungary flag Tervezői felület

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Diamond coatings can be deposited by many methods.  Presently, the most favoured technique is microwave plasma CVD.   Diamond coatings are crystalline and are usually characterised by a combination of methods which include, Raman spectroscopy, X-ray diffraction and surface morphology.    Also see hot filament CVD

Hungary flag Gyémánt bevonatok

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A very hard (≈3000-4000 kg/mm2) carbon coating with little or no crystallinity (amorphouis).    Initially such coatings proved unsatisfactory for tribological protection because of poor substrate adhesion and unfavourable residual stress.  Some recent progress has been made whereby appropriate sub-layers of transition metal carbides and nitrides are deposited prior to deposition of a DLC.   This is particularly important when deposity DLC onto metallic substrates.  DLC's can be deposited by sputter deposition or plasma assisted CVD

Hungary flag Gyémánt-szerű bevonatok (DLC)

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Any process that produces a surface enriched in another element through solid state diffusion and (usually) resulting in the formation of intermetallic or interstitial compounds.  Processes include aluminising, boriding, chromising, sheradising, siliconising  and vanadising.  By convention, it specifically excludes carburising, carbonitriding, nitriding, and nitrocarburising.

Hungary flag Diffúziós bevonat

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That time of a thermochemical treatment when the active specie(s) diffuse into the substrate.   To provide distinction from, for example, the heating and cooling cycles.

Hungary flag Diffúziós idő

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The concentration of elements in the diffusion zone following a thermochemical diffusion treatment.  Also see concentration profile.

Hungary flag Diffúziós eloszlás

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A  term first invoked by Trent and Loladze in the 1950's, to account for the rake face cratering of cemented carbide cutting tools, observed after cutting plain carbon and low alloy steels at relatively high speed (>100m/min). Other workers have termed this effect "dissoution/diffusion wear" or "solution wear".  For cemented carbide tools, comprising WC-Co or WC-(W,Ti, Ta,Nb)C-Co (termed "straight grade" and "steel cutting grade" carbides respectively),  the WC grains become smoothly worn.   In the case of "steel cutting grade" cemented carbides, microsections, made normal to the rake face surface, reveal that the WC phase is preferentially worn; the (W,Ti,Ta,Nb)C phase being less severely worn, stands proud of the adjacent WC grains.  The preferential wear of the WC phase is attributed to its higher solid solubility limit in g-Fe (present in the steel chip shear zone during cutting) compared to that of the (W,Ti,Ta, Nb)C phase.

Other tool materials, like high speed steel and ceramics can be worn by this type of mechanism, e.g., when sialon tools are used to cut low alloy and plain carbon steels at cutting speeds above 200 m/min; similarly Al2O3-ZrO2 ceramics exhibit a similar effect when used to cut titanium alloys at cutting speeds above 50 m/min.  TiN and TiC coatings, deposited by PVD or CVD, are also worn in this way when used to cut steels above 100 m/min although other mechanisms like discrete plastic deformation make a significant contribution.   For further details see "Metal Cutting" by E.M. Trent, Butterworths, 3rd Edition, 1992.

Hungary flag Diffúziós kopás

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A term used especially in connection with nitrided steels.  In this xample it refers to the zone of coherent nitride precipitation, residing beneath the compound layer, which constitutes 95 to 99% of the depth of the nitrided "case".   The nitrogen content of the diffusion zone ranges from nearly 20at-% adjacent the compound layer to below 1at-% adjacent the core structure

Hungary flag Diffúziós zóna

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Any technique whereby a coating is formed by immersing a solid in a liquid which subsequently bonds to the solid surface.   The most common types include hot dip aluminising or hot dip galvanising.  The term also refers to coating by immersion in ceramic slip or even polymeric solutions (organic paints). 

Hungary flag Mártással történő bevonás

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A common wear mechanism of PVD and CVD ceramic coatings (TiC, TiN and Al2O3) when used to cut steel at speeds above 100 m/min.   The mechanism increases with increasing cutting speed (temperature) and is the principal rake face wear mechanism of Al2O3 coated cemented carbide tools.   The mechanism culminates in the removal of wear fragements through ductle fracture (see daigram, sequence 1 to 4).  It should be appreciated that coating temperatures often exceed 1100°C when cutting steel; at these temperatures TiC, TiN and Al2O3 behave plastically.       Also see P. A. Dearnley,  R. F. Fowle,  N. M. Corbett and D. Doyle,  Surface Engineering, 1993, 9, 312-318.

Hungary flag Diszkrét képlékeny alakváltozás

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See diamond-like coatings

Hungary flag DLC

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The process of removing residues from washing operations by means of hot or cold air, freon, infra-red radiation or contrifugal action.

Hungary flag szárítás

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A combination of two sequential (and mutually compatible, from the treatment temperature perspective) surface engineering methods to achieve a synergistic surface property design.   At the time of writing, much interest is being shown in extending the application range of thin (≈5µm) ceramic coatings (like TiN and TiC) to low yield strength (≈500-1000M.Pa) substrates by prior strengthening via a thermochemical diffusion treatment.  Feasible duplex treatments include: (i) CVD after carburising, followed by quenching (to permit the g-Fe --> a'-Fe transfomation); (ii) PVD after nitriding.   Note: carburising temperatures ≈ CVD temperatures; PVD temperaturs ≈ nitriding temperatures.  Initial trials have been carried out in two distinct operations.  More recent efforts have focused on enabling each process to be carried out sequentially in the same vessel.

Hungary flag duplex felület technológia

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The ability of a surface engineered material to endure in-service wear, corrosion or fatigue.

Hungary flag tartósság

E

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Energy dispersive analysis by X-rays.   An electron beam (≈20-30 KeV) is focused onto a the sample surface, which must be electrically conducting; among the many surface effects, X-rays, of characteristic energy are produced.   An optimal sample-electron beam distance is used to assure X-rays of sufficient intensity are brought to focus at a solid-state detector, chilled to liquid nitrogen temperature.   The detector is frequently isolated from the microscope vacuum chamber by a Beryllium window.   X-rays with an energy in the range of 1 to 20 keV are efficiently detected allowing the simultaneous detection of all elements heavier than boron, using at least one of the principal K, L, or M emission lines.   Some modern devices have ultra-thin windows or offer windowless detectors allowing the detection of elements down to Li.  However, it should be appreciated that the detection of low atomic elements below oxygen, is accompanied by a poor signal to noise ratio, making even semi-quantitative analysis difficult.   Quantification of heavier elements is easier; nowadays this is achieved routinely by dedicated computer software.  The method is very rapid.   EDX is an excellent tool for gaining an immediate idea of chemical composition.   Elemental mapping, in conjunction with secondary electron imaging is also a useful feature of this method.    For high accuracy chemical composition analysis, however, EDS is inferior to WDX.   The latter method is significantly better for light element analysis

Hungary flag EDX

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The techniques of forming coatings via electroplating or electrophoresis.

Hungary flag Elektro-bevonatolás

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A high power density beam generated by a device termed an electron gun.  This comprises a pair of anular electrodes and a resistively heated tungsten filament which emits electrons via thermionic emission.  The electrons are accelerated by respectively passing them through the centres of an anular cathode and anode.   After exiting the gun, the electrons are focussed by an electromagnetic field, generated by a solenoid.  Very high accelerating voltages can be used (≈500 KeV) and power densities of 106 to 107 W/cm2 are easily achieved.   Higher power densities are achievable by operating in pulse-mode; a similar principle to that deployed in Nd-YAG and excimer lasers.   In surface engineering an eletron beam is complimentary to a laser.    It is used as an evaporation device, e.g., in ion plating, or for surface alloying and transformation hardening of metallic materials.   Energy coupling to metallic surfaces is outstanding, but elelctron beams have the disadvantage of not been applicable to non-conducting surfaces, like dielectric ceramics (e.g., Al2O3).   Despite development devices that have demonstrated the feasibility of operation at atmospheric atmosphere (e.g, see Y. Arata: 'Plasma, Electron & Laser Beam Technology'; 1986, Ohio, American Society for Metals), the routine industrial use of electron beams remains restricted to the confines of a vacuum chamber (minimum pressure ≈10-4 torr).

Hungary flag Elektron sugár

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Carburising involving electron beam heating of surfaces into the austenitic range.  The carbon can be supplied as a gaseous hydrocarbon, but more readily as a pre-placed graphitic surface coating.   During electron beam heating, the carbon dissolves into the austenite and the structure is allowed to self-quench by conducton into the relatively cool core.  Treatment depths are relatively shallow <50 µm.   The technique is not widely used.

Hungary flag sugras cementálás

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An electron beam treatment applied to a metallic surface which is momentarily surface melted to enable the encapsulation of preplaced or injected ceramic powder particles.   The treatment is applicable to ferrous or non-ferrous metals and alloys.  There has been a lot of interest in recent years in applying such treatments to aluminium and titanium alloys because both suffer from the disadvantage of responding poorly to conventional thermochemical diffusion treatments, i.e., they develop very shallow treatments, if any.   Electron beam cladding offers the possibility to develop deeply hardened surfaces, up to 1 mm.   The process is analogous to laser cladding.

Hungary flag Elektron sugaras bevonatolás

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An ion plating or vacuum evaporation process that uses an electron beam (eb) to vapourise the metallic source constituent(s) of a coating.  It is requirement of such devices that the electron beam should be housed in a differentially pumped vacuum chamber attached to the main vessel.   This enables the electron beam to operate at the preferred pressure of 10-4 torr while allowing a glow discharge plasma to be created at higher pressure, ≈10-2 torr, in the main deposition vessel (diagram).     The electron beam is steered into the main chamber, via a small aperture, using a system of electromengnets.   Sufficient power density is available to vapourise even refractory metals like tungsten and molybdenum.   Also see ion plating.

Hungary flag Elektron sugaras párologtató PVD

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An electron beam treatment aimed at producing an amorphous/glassy surface layer.  It involves electron beam heating a surface with power densities ≈ 105 to 107 W/cm2 and interaction times ≈ 10-3 to 10-7 seconds; subsequently the surface rapidly solidified at cooling rates exceeding 105 K/s, which suppresses the nucleation and crystallisation processes, thereby promoting vitrification/amorphortisation.   Less widely practised than laser glazing.

Hungary flag Elektron sugaras polírozás

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A process involving electron beam heating of the surface layer of a steel into the austenitic temperature range followed by rapid self-quenching by conduction into the relatively cool core.  The process produces relatively low distortion.  It is claimed to be more economic than laser transformation hardening.

Hungary flag  Elektron sugaras felület edzés

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Any heat treatment utilising an electron beam as the principal heat source. 

Hungary flag Elektron sugaras kezelés

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The electrodeposition of thin adherent layers of metals or alloys onto a metallic substrate, thereby creating a composite material whose surface properties are dominated by those of the coating.   Chromium and nickel plating are probably the two commonest forms of electroplating.   Developments in electroplating technology include: pulse plating, modulated current plating, superimposed current plating and periodic reverse current electroplating.

Hungary flag fémbevonás

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Surface finishing of metallic objects by making them anodic in an appropriate electrolyte, whereby high points are preferentially dissolved, resulting in a bright and level surface with high specular reflectivity.  In a sense the process can be likened to electroplating in reverse, i.e., the articles are anodic, while in electroplating they are cathodic.   Hence, the process is sometimes called reverse current cleaning or anodic cleaning.   A wide variety of metals and alloys can be electropolished, they include: aluminium, stainless steels, brass, copper and nickel-silver.   Polishing solutions are genereally based on phosphoric acid and are used at a current density ≈15 to 80 amp/dm2.

Hungary flag Elektro-polírozás

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A fluidized-bed method of coating parts with plastic/polymer.      A d.c. high voltage electrode is used to electrostatically charge polymer powder particles which become attracted to the electrically grounded surfaces of the objects being treated.  Following deposition, the objects are heat treated in an oven; this is set to a temperature sufficient to cause melting of the polymer and simultaneously enable good bonding to the metallic surface beneath.   Before coating steel parts, it is important to vapour degrease and grit blast the component surfaces, followed by phosphating or chromating.  Also see fluidized-bed coating with plastics.

Hungary flag Elektrosztatikus fluid-ágyas bevonatolás

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A method of spray depositing polymeric coatings onto metals, especially steels.   A fine polymer powder is fed from a hopper into an air stream and passed through a hand held spray pistol where it becomes positively charged using a voltage ≈20-60 kV.  The powder is projected out of the pistol as a fine aerosol.    The powder particles are electrostatically attracted to the workpiece surfaces which are electrically grounded.   Overspray is collected by a cyclone or forced extraction system containing filters.   Following deposition, the objects are heat treated in an oven; this is set to a temperature sufficient to cause melting of the polymer and simultaneously enable good bonding to the metallic surface beneath.  This method is a good technique for producing relatively thin polymer coatings (≈50 to 200 µm), but capital cost of the equpment is quite high.   Nylon is commonly applied by this method.     Before coating steel parts, it is important to vapour degrease and grit blast the component surfaces, followed by phosphating or chromating.   Also see flame spraying of plastic coatings.

Hungary flag Elektrosztatikusan felvitt műanyag bevonatok

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The ratio of the total emissive power density (W/cm2) of a heated object to the emissive power density of a perfect black body radiator at the same temperature.  The nearer to unity, the more perfect the emissivity.   A dimensionless quantity.   Symbol e.

Hungary flag emissziós tényező

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See vitreous enamel coating.

Hungary flag porcelán

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The procedure of applying a vitreous enamel coating.  See vitreous enamel coating.

Hungary flag Bevonatolás porcelánnal

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A controlled atmosphere produced by the catalytic decomposition of a hydrocarbon gas in a heated chamber’ – IFHT definition

Hungary flag Endotermikus atmoszféra

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The following processes can be regarded as non-invasive on the environment:- plasma nitriding, PVD of transition metal nitrides and carbides, plasma spraying (APS and VPS) and nitrotec.   Meticulous safety precautions and environmental safe guards are required when operating most salt bath methods, CVD, boronising and gaseous carburising processes.

Hungary flag A felületi technológiák környezeti hatása

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Most commonly observed for coated single crystals (like silicon wafers), where a definite crystallographic orientation relationship exists between the coating and substrate.  Epitaxy can be subdivided into homoepitaxy and heteroepitaxy.   Homoepitaxy refers to the situation where the  coating and substrate are made of the same material; heteroepitaxy refers to the situation where the  coating and substrate are made of dissimilar materials.

 Hungary flag epitaxia

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A plastic coat containing thermosetting epoxide resins.  They have excellent adhesion and chemical resistance.  

Hungary flag Epopxy-gyanta bevonat

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A form of wear produced by the action of hard particles, suspended in a fluid (gaseous or liquid), repeatedly impacting on a solid surface.    Particle velocities are usually in the range of 5 to 500 m.s-1.   Also termed slurry erosion, when the fluid is liquid.  

Hungary flag erózió

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Wear taking place by the mechanism of erosion.  Commonly found in soil engaging tools, hydro-electric plant, beach-landing marine craft and aircraft components operating in desert environments

Hungary flag Eróziós kopás

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Electron Spectroscopy for Chemical Analysis.   An umbrella term for the high vacuum surface analysis equipment configured for both XPS and AES techniques.

Hungary flag ESCA

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(i)  a shallow chemical cleaning aimed at removing surface oxides or passive films by immersion in an appropriate acid or alkaline solution;  (ii) a glow discharge cleaning process for the removal of passive oxide layers; usually achieved more efficiently with an RF rather than a DC plasma.  Plasma etching is frequently a preparatory step before plasma assisted PVD.

Hungary flag maratás

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A device, such as an electron beam or electric arc, used to vapourise the solid source component of a coating in evaporative source PVD.   

Hungary flag párologtató berendezés

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See spalling

Hungary flag rétegszétválasztás

F

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A term widely used in the electronics  industries relating to thin (usually  <1 µm) coatings applied to so called thin-film devices.   Such coatings are frequently insulating or semi-conducting in their electrical character.

Hungary flag film

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A well established computational technique for determining the distribution of stresses in engineering structures under load.  FEM has found recent use in surface engineering for  the prediction of elastic stresses in low modulus metals coated with high modulus ceramic coatings during point contact loading.

Hungary flag Végeselem módszer (F.E.M.)

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Sometimes called shorterizing.   A convenient method of transformation hardening, requiring less capital investment than induction hardening.   Oxyacetylene or oxygen-propane gas torch(es) provide the required heating to raise the surface temperature of medium carbon steels (≈0.3-0.5wt-%C) into the austenitic range; susbsequently the heated parts are quenched by spraying with water jets or by immersion in a quench tank, thereby developing the required martensitic case.    There are three main types of flame hardening:  (i) manual hardening comprises heating the objects to be hardened with a hand held torch. This method is useful for hardening small surface areas and small numbers of parts; (ii) spin hardening is employed for components with rotational symmetry; here the torches are mechanically fixed while the components are rotated on a motorised platform-fixture; (iii) progressive hardening is used for hardening flat surfaces or long sections, like machine slide-ways.   The torch is passed over the surface, or the part is passed under a fixed torch,  at speeds ≈50 to 200 mm/min.   Immediately located behind the torch is a cold water jet which provides the quench medium.  Also see induction hardening.

Hungary flag lángedzés

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A relatively low cost method of applying polymeric coatings (>200 µm thick) to metals, especially steels.   The workpieces are preheated and immersed into a bed comprising fluidised polymeric particles, which melt on coming into contact with the pre-heated surfaces, thereby forming a dense polymeric coating.  The technique requires significant operator skill.   Before coating, it is important to vapour degrease and grit blast the component surfaces, followed by phosphating or chromating.  Also see electrostatic fluidized-bed coating  and electrostatically sprayed plastic coatings

Hungary flag Fluid-ágyas bevonatolás műanyagokkal

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Fluidized beds can be used to provide rapid thermochemical diffusion treatments; since heat transfer is rapid the time to achieve the required treatment temperature is shorter than for many other thermochemical diffusion methods (except salt bath methods).   The most common examples where fluidized bed technology is exploited are nitroarburising, nitriding and carburising; boriding has also received investigation but is not very commonly practised.   All these processes utilise a fluidised bed of inert material (often aluminium oxide - corundum) through which appropriate gases (similar to those already described for the equivalent gaseous treatments) are passed.    Fluidised-bed operations are intrinsically dusty and stringent working practices are required in order to maintain an acceptable level of workshop cleanliness.

Hungary flag Fluid-ágyas termokémiai diffúzós módszerek

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In the context of surface engineering, the ability of a plastic or metallic coating to adapt to changes in shape without flaking or cracking.   A common quality required of coated steel sheet.

Hungary flag alakíthatóság

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Wear caused through high frequency (kHz), low amplitude (<5 mm) sliding contact.

Hungary flag Súrlódási korrózió

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A mechanical surface engineering treatment in which a consumable rod is rotated at high speed and applied to a surface under high axial load thereby creating sufficient frictional heating to melt the rod, which becomes layed down as a deposit.  The technique can be applied to flat surfaces, plate edges, annular discs and even shafts.  The composition of the rods are not openly disclosed but are thought to contain various transition metal cabides. The treatment is used to provide wear protection .

Hungary flag Surlódási felületkezelés

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Any surface finishing treatment which produces a surface with a fine matt appearance,  e.g., blasting, brushing, barrelling and etching.  Sometimes applied to glass for decorative affect.

Hungary flag dermedés

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Also known as  "self-fluxing overlay coatngs".   Applied to an object by firstly thermospraying and secondly fusing with an oxyacetylene torch or an RF induction coil, which "wets" the coat to the substrate.   This produces a coating that is metallurgically bonded to the substrate and is free of microporosity.  Hence, it is impervious to corrosive fluids.   This two-step method of application is known as the "spray and fuse process".  There are various alloy types, the most important of which are based on the Ni-Cr-B-Si-C system; depending upon the exact alloy composition, they melt in the range of 980 to 1200°C.     The constitution of the Ni-Cr-B-Si-C coatings are complex, but frequently contain relatively large Cr7C3 carbide particles  (≈10 - 100 µm) in a nickel rich matrix.  Some compositions also produce coatings that contain chromium borides.   The coatings show excellent resistance to abrasion wear (under light loading) and are particularly effective in resisting the conjoint action of corrosion and abrasion, e.g., in certain marine applications.    Another composition contains additives of coarse (≈150µm) tungsten carbide particles which serve to  improve abrasion resistance even further.

Hungary flag keményfém felrakás

G

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An electrochemical cell having two dissimilar electrical conductors as electrodes.

Hungary flag Galván-cella

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A method of hot dip coating whereby steel, typically in sheet from, is immersed into a bath of molten Zn-5wt%Al alloy held at approximately 450°C.   Under optimal processing conditions, a coating free from from massive interfacial intermetallics, is produced.  Instead, a fine lamella microstructure, containing h-Zn (a solid solution of iron in Zn) plus q-FeAl­3 and h-Fe2Al5 intermetallics, is formed throughout the coating.  This method has been developed as an alternative to galvanising.   Also see galvaluming.

Hungary flag galvanizálás

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(i)  A traditional term for flash gold (24 carat) plating of fancy goods, trinkets and giftware sold at the cheaper end of the domestic market. See gold plating.  (ii) The mechanical application of gold leaf (0.076 to 0.127 micrometers thick) to wooden or base metal objects.

Hungary flag bevonás aranyfüsttel

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A relatively recent (circa 1979) optical emission spectroscopy technique that has the capability to analyse a large number of elements.   The design of the sample chamber is based on the Grimm lamp.  The sample is made cathodic with respect to an anular anode (≈ 8mm in diameter) through which a low pressure flow of argon is passed.  A current intensive glow discharge plasma is subsequently created at a pressure ≈ 1.5 torr and material is removed from the sample face by high rate sputtering.   Whilst in-flight the excited sputtered sample atoms emit photons of characteristic wave-length (due to electronic transitions); see diagram.   The light is then focused and passed through a colimating slit into a spectrometer where it strikes a concave holographic grating, splitting the light into its component wave-lengths.  The spectral detection range is ≈110 to 1000 nm. The system must be calibrated against primary standards, but can routinely analyse all the major elements including, hydrogen, nitrogen, carbon, oxygen and boron.  It also has the capability to achieve rapid depth profiling, making the technique of special value for the analysis of ceramic coatings and diffusion zones.   For example, it is possible to analyse 10 elements to a depth of 50 µm in less than 30 minutes.   However, some experiences show that depth resolution would not appear to be better than 0.5µm.

Hungary flag Izzítási optikai emissziós spektroszkópia

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Base metals, like zinc and brass castings, are given a prior bright nickel electroplate deposit.   Gold plating (gilding) is costly and hence electroplating is carried out for very short times (typically ≈5 to 15 seconds).  Hence, the term flash gilding.   For filigree work (delicate ornamental objects made from wire) thicker coatings are needed and electroplating is therefore carried out for 20 to 30 seconds.

Hungary flag bevonás aranyfüsttel

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Any coating whose constitution varies continuously between successive layers, usually enabling a progressive blending of properties between that of the substrate and the outermost layers of the coating.  Coatings of this type can be produced by thermal spraying or plasma assisted PVD methods.

Hungary flag fokozatos bevonatolás

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A process for removing rust, paint or unwanted surface deposits (e.g., flash) from components.   A high velocity air stream is used to propel angular shaped alumina or silicon carbide particles onto component surfaces at high speed.  The flow is directed through a flexible hose and nozzle, enabling manipulation of the flow direction.  Grit blasting is a common preparation stage prior to thermal spray coating.

Hungary flag Homokolás

H

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A term usually referring to transition metal carbides and nitrides deposited by CVD or plasma assisted PVD methods, e.g., TiC and TiN, which have Vickers hardness values in excesss of 2000 kg/mm2.   The term hard coating tends to be invoked when these coatings are being applied in order to improve wear resistance of various items,  e.g., metal cutting tools or bio-medical prosthetic implants.

Hungary flag Kemény bevonat

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Jargon for hard chromium or hard nickel plating, but usually the former.

Hungary flag Kemény lemezelés, bevonás

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Qualitatively, a measure of the resistance of a surface to penetration by an indenter. Quantitatively, a measure of yield strength. For example, Vickers hardness Hv is related to yield strength (sy) by the approximate relationships:

Hv ≈ 3 sy (for metals and alloys)

Hv ≈ 4 sy (for ceramics)

Hungary flag keménység

:

Various methods of hardness determination exist.  These can be broadly grouped into: (i) static and; (ii) dynamic hardness methods.  In surface engineering only static methods are used.   These comprise Vickers, Knoop and Berkovich diamond indentation methods.   Rockwell hardness on scales A, B or C is used in accordance with the type of material; most popular in the United States and unsuited to microhardness determination.   See Vickers hardness, Knoop hardness, and Berkovich indentation hardness.

Hungary flag Keménység mérés

:

Also sometimes termed hardness distribution.  In surface engineering it specifically refers to microhardness as a function of depth below the surface.   The shape and magnitude of such curves are often a signature of a given type of treatment.   "S" shaped curves are a characteristic feature of nitrided or carburised steels (see below) while single step-like curves are typical of hard coated ferrous or non-ferrous alloys.   Hardness profiles are most easily determined using Vickers or Knoop hardness  indentation methods.  Also see Vickers hardness, Knoop hardness, Berkovich indentation hardness  and nanoindentation hardness.

Hungary flag Keménység eloszlás

:

The manipulation of bulk and surface properties of a material by the concise application of heating and cooling cycles, in an appropriate atmosphere.  For steels, comon bulk heat treatments include, annealing, hardening & tempering, normalising, stress relieving and sub-critical annealing.   Some common "surface heat treatments", include carburising, nitriding, nitrocarburising and boriding

Hungary flag hőkezelés

:

In surface engineering this refers to the HAZ beneath a power beam alloyed or clad surface, i.e., the zone, adjacent the formerly liquid region, which remained in the solid state for the entirety of the treatment, but whose microstructure has been changed from that of the core, as a result of rapid heating and cooling.

Hungary flag tűzi ónozási zóna

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Cone cracks formed on the surface of a brittle elastic solid (e.g., ceramics and glass) resulting from the high contact stresses exerted during point contact loading by a spherical indenter (or similar).    Note: in sliding contacts ring shaped cracks are replaced by a series of overlapping arc-shaped cracks.   This effect can also be seen following scratch testing.

Hungary flag Hertz repedések

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A situation whereby a high yield strength and/or high modulus coating fails through plastic flow of a low yield strength substrate during intensive point contact loading (diagram).   Sometimes referred to as the "thin ice effect".   Also see Hertzian stresses.

Hungary flag Hertz törés

:

The Hertzian elastic contact stresses developed, for example, when an indenter contacts a planar surface. The shape of the elastic stress field and the position of the maximum resolved shear stress depends upon indenter geometry, while the magnitude of the compressive and shear stresses (for a given contact force) is dependent upon the elastic moduli and Poissons ratios of the indenter and planar materials. For a spherical indenter, indenting a planar surface, the radius of circular contact (a) is given by:

a = (3FR/4E*)1/3

where:

F = Applied load (N)

R = radius of the indenter (m)

R = radius of the indenter (m)

E* = ((1-u12/E1) + (1-u22/E2)) -1

E1 = indenter Young's modulus (G.Pa); u1 = Poissons ratio of indenter

E2 = Young's modulus of the semi-infinite surface (G.Pa); u2 = Poissons ratio of semi- infinite surface

The maximum contact pressure Pm (M.Pa) at the contact interface is given by:

Pm = (3F/2pa2) = (6FE*2/p3R2)1/3

The shear stress t is zero at the contact interface but achieves its maximum value along the indenter centre line at a position that is exactly 0.48a beneath the planar surface. The magnitude of tmax (M.Pa) is simply related to Pm:

tmax = 0.31 Pm

For a cylinder contacting a planar surface the Hertzian equations are modified, but it is worth noting that tmax = 0.30 Pm (very close to the relationship for a spherical indenter), whereas, the position of the maximum shear stress, is exactly 0.78a beneath the planar surface. Hence, when considering tribological situations where third body particles are present, the particle (or indenter) shape has a very strong influence on the position of the maximum shear stress. This has implications for coating design specifications. Coating "X" maybe of adequate thickness for avoiding sub-surface yielding by spherical particles, but maybe inadequate for avoiding sub-surface yielding by cylindrical or rod-shaped particles. For a more rigorous mathematical analysis the reader is referred to K. L. Johnson's, "Contact Mechanics", Cambridge University Press, 1987.

Hungary flag Hertz feszültség

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A qualitative term referring to high power density heat sources, like lasers and electron beams.

Hungary flag Nagy energiájú sugarak

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A similar concept to high velocity oxygen fuel (HVOF) spraying except this particular design of torch has the economic advantage of running on a mixture of air and kerosene (paraffin).   Particle velocities are claimed to be equivalent to those obtained with HVOF.   This technology has been devised by the Browning Corporation (USA).  A variety of coatings can be deposited, but WC-Co is one of the more common.   Also see detonation gun spraying  and high velocity  oxygen fuel (HVOF) spraying.

Hungary flag Nagy sebességű lég-fűtőanyag fújás

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Originally developed by the Browning Corporation (USA) this process pre-mixes oxygen and a fuel gas like acetylene and passes them into a flame nozzle where they are ignited to produce a ring of "flame jets".    With the help of a carrier gas, coating powder is injected along the the central axis of the combustion flame.   Very high particle velocities are achieved.  There is some contention regarding the precise particle velocities but these are generally agreed to be several times those achievable with plasma spraying.  One claim is that they reach ≈1000 m/s, which should be compared with ≈150 m/s for plasma spraying.    It is claimed that the coatings produced are of comparable density, if not superior, to vacuum plasma sprayed coatings.    The manufacturers of HVOF and HVAF systems also state that the powder particles receive significant heating on impacting the component surface.   There is contention regarding the relative proportions of heat imparted to the powder particles during impact and that imparted by the torch "flame".     A variety of coatings can be deposited, but WC-Co is one of the more common.   One commercial torch of this type goes by the name of "Jet-Kote".   Also see detonation gun spraying  and high velocity air fuel (HVAF) spraying.

Hungary flag Nagy sebességű oxigén-fűtőanyag fújás

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A quality control test used for determining surface connected porosity or microdefects in paint or plastic film (if applied to metallic objects).     The substrate is connected to one side a DC power supply, while a  high voltage (low power) metal probe is passed over the treated surface.  Any micro-defects in the coating results in the closure of the electrical circuit, and the triggering of an audible or visual signal.

Hungary flag Holiday teszt

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A current intensive effect observed when two cathode plates, surrounded by a glow discharge plasma, come into close proximity, such that their respecive dark spaces or glow seams overlap.   The situation may also arise inside a hole within a negatively charged component, as for example during plasma nitriding.   The magnitude of the discharge current is inversely proportional to the cathode plate separation (see diagram below, based on data from N. A. G.  Ahmed and D. G. Teer, Thin Solid Films, 1981, 80, 49-54) or hole diameter.   At some critical spacing, current densities can be sufficient to melt many metals in a matter of a few seconds.    With experience, however, such catastrophies can be avoided.  A useful exploitation of the hollow cathode effect is the hollow cathode source evaporator.   See hollow cathode source evaporative PVD.

Hungary flag Üres katód

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Immersion of steel plate (usually) into molten zinc or Zn-Al alloy (0.1 to 0.3wt-% Al) to produce a protective surface coating some 80 to 125 µm thick.    The bath temperature is normally 430-460°C.    Pre-treatment of the steel may include annealing in a reducing atmosphere, acid-pickling and fluxing with zinc chloride.  After hot dip galvanising,  an annealing or diffusion treatment (sometimes called galvannealing) may be carried out to substantially improve outdoor corrosion resistance,   spot weldability and paintability.   Galvanised layers have a complex constitution but often comprise a mixture of  g-Fe5Zn21,  d-FeZn7 and x-FeZn13 and h-Zn (a solid solution of iron in Zn).     Generally, the g-phase comprises <5% the thickness of the total layer, the remainder being  dominated by  d, x  and h.   Some workers give g-Fe5Zn21 as G1-Fe5Zn21 and suggest the phases  G-Fe3Zn10 and d1-FeZn10  are also important.   For further details see J. Mackowiak and N. R. Short,  Int. Met. Rev., 1979, 24, 1-19.

Hungary flag Forró merítő galvanizáció

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Hot dip tin has a corrosion resistance similar to that of zinc and,  because of its low toxicity,  is used for the corrosion protection of steel used in the food processing industry.  Processing steps are similar to galvanising; the metal sheet, for example, is prepared by pickling and fluxing followed by immersion in molten tin for a short time.  Steels, copper and copper alloys can be hot dipped in this way.  Deposits are ≈12-50 µm thick.   

Hungary flag Forró merítő ónozás

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A lubrication situation whereby two sliding surfaces are separated by a relatively thick film of lubricant and the normal load is supported by the pressure within the film which is created hydrodynamically.   Both sliding surfaces must have conforming geometries to enable the establishment of hydrodynamic lubrication.   Contrast with elastohydrodynamic lubrication (EHL).

Hungary flag Hidrodinamikus /áramlástani kenés

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A problem encountered in chromium or nickel plated steel objects, whereby significant quantities of hydrogen, evolved during electroplating or prior alkaline or acid cleaning/pickling,  becomes dissolved in the steel and impairs toughness and ductility.  Such hydrogen can be removed, or redistributed, by 'baking'  to ≈200°C.  However, if fatigue strength is of critical importance, baking must be carried out above 450°C, or not at all, since baking at 200°C causes a major reduction in fatigue strength, even compared with 'unbaked' material.

Hungary flag Hidrogén ridegség

I

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Small articles made of brass or copper can be given a flash coating of gold by a simple immersion method.  The gold is deposited by a displacement reaction.  Immersion gilded items include domestic fashion ware, printed circuit boards and electrical bridging pieces.

Hungary flag Merítéses bevonatolás

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A mechanical treatment in which the surface is hardened by repetitive cold working, e.g.,  by bombarding with small hard particles (peening) or by hammering.

Hungary flag Ütéses felületkezelés

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Quantity of ions implanted into a surface, typically residing in the range of 1017-1018 ions/cm2.    See ion implantation.

Hungary flag Ion implantációs dózis

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A rapid method of surface hardening applied to steels of medium carbon content ≈0.3 to 0.5 wt-%.   The steel should be at least in the normalised condition, but preferably hardened and tempered, providing sufficient bulk strength for heavy duty applications.   Fully annealed steels are unsatisfactory for most purposes.   A high frequency induction coil (0.5 to 500 k.Hz) is used to induce eddy currents into the steel surface which causes rapid heating.   There is much craft, as well as science, in the design of a given induction coil for a particular application, and most heat treatment shops have a range of coils for various purposes.   Immediately following austenitisation of the surface the component is allowed to self quench (by heat transfer into the relatively cooler core) or maybe quenched by appropriately positioned water jets.  After hardening, tempering at ≈150 to 200°C is carried out to avoid excessive brittleness.  This is especially important if the parts are to be subsequently ground (to obviate cracking).

The power input of induction coils lies in the range of 0.1 to 2.0 kW/cm2.  Choice of frequency depends upon the depth of treatment required per second of interaction time.   Simplified relationships exist to enable calculation of the approximate depth of the heat affected zone (dh) for steel up to the hardening temperature.   For example, at 800°C;  dh ≈ 100/√ƒ, where ƒ is the induction frequency in Hz.   Hence, high frequencies ≈ 250 k.Hz are used where shallow treatments ≈ 0.2 mm are required, while low frequencies ≈ 4 k.Hz are used where deeper treatments ≈ 1.6 mm are required.   Induction coil diameter and the number of turns in a particular coil, are also of importance.   Also see flame hardening.

Hungary flag Indukciós felületkeményítés

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Surface tempering using induction heating.  The tempering time in this process is extremely short and localized.  For large surface areas, furnace tempering is mandatory.

Hungary flag Indukciós hőkezelés

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Gas analyser of the absorbtion kind, factory set to determine ammonia or CO/CO2 levels in gaseous nitriding and carburising furnaces respectively.   It works on the principle that when infra-red radiation (l = 2 to 11 µm) passes through a gas certain gases absorb the radiation in accordance with the amount of gas present.   Elemental gases do not absorb infra-red and hence cannot be detected by this technique; a mass spectrometer would have to be used in such cases.

Hungary flag Infravörös-gáz elemző

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Any substance added to an environment in relatively small quantities which serves to reduce the corrosion rate of objects placed in it.

Hungary flag Korrózió késleltető

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Oxidation involving precipitation of dispersed oxides within a metal sub-surface, while oxygen is supplied from the surface via diffusion.   For steels,  internal oxidation is analogous to nitriding.

Hungary flag Belső oxidáció

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Any method that deploys an ion beam or plasma that (directly or indirectly) achieves a change in surface properties.

Hungary flag Ion segítette felületkezelés

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Any beam of ions generated by any method.   Energies may vary widely depeding upon the application.   These could range from ≈100 ev to ≈100 kev.  For example see ion implantation.

Hungary flag Ion nyaláb

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A hybridised process, whereby a plasma assisted or non-plasma PVD process is supplemented by an ion beam which is used to bombard the substrate surface before and/or during deposition.    Sometimes used in conjunction with balanced magnetron sputter deposition techniques to improve coating adhesion.  This procedure is now obviated, to some extent, by the invention of the unbalanced magnetron sputtering source.    Also see ion beam sputter deposition.

Hungary flag Ion nyalábos bevonatolás

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A surface treatment whereby atoms from the surface of an object are removed by the sputtering action of an impinging high energy ion beam.    The efficiency of this process depends on ion mass, ion energy, angle of incidence of the ions, physicochemical state of the surface, and temperature.  Argon ions are usually preferred.   Ion beam sputter cleaning is widely used as a means of preparing sample surfaces for interrogation by surface analytical methods, especially AES, XPS and SIMS.

Hungary flag Ion nyalábos tisztítás

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A sputter deposition process in which (usually) argon ions, generated in an ion beam gun, are used to remove atoms from a target surface by the mechanism of sputtering.  The sputtered atoms recombine at a substrate surface and form a coating.  This process falls within the plasma assisted PVD classification and permits the sputter deposition of magnetic and dielectric materials.   It is usually performed at a lower pressure than magnetron sputtering.

Hungary flag Ion nyalábos bevonatolás

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A method of modifying surface microstructure and properties, whereby high energy ions (≈1017-1018 ions/cm2) are implanted into the surface and sub-surface of a material, to a depth that increases in proportion with the incident ion energy.      Nitrogen is the most popular ion, but a wide variety of metallic and non-metallic ions can also be implanted.   The technique causes a marked hardening of metallic surfaces, and, depending upon the implanted element, some improvement in corrosive-wear resistance is observed, e.g., the Ti-6Al-4V shows improved corrosive-wear resistance in saline environments after implantation with 3.5 x 1017 ions/cm2 of nitrogen (equating to a concentration of ≈ 20 atomic%).   Chromium implantation has also been observed to improve the corrosion resistance of plain carbon steels.

Hungary flag Ion implantáció /beültetés

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The original term for plasma nitriding first used by Klockner Ionon;  the term has been superseded by plasma nitriding.

Hungary flag Ion nitridálás

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A proprietry name (circa 1974) used by the McDonnel Aircraft Company (USA) for their ion plating system used for coating aerospace components (principally steel fasteners) with aluminium for corrosion protection.   The technique was devloped to replace cadmium plating which was banned because of its high toxicity.   Three common coating thicknesses are used: 7.5 µm, 12.5 µm and 25 µm.   The thicker coatings provide the greatest longevity of corrosion resistance.   Thin coatings are used where compliance to small tolerances is required, e.g., on the threads of certain fasteners.   Following deposition, it is usual practice to glass bead peen the coatings.    This helps close micropores and provides a smoother surface finish.  At this juncture parts with poorly adhered coatings can be identified and scrapped.  Apart from steel, numerous titanium and aluminium alloy aircraft components are regularly coated.  These include electrical connectors, fuel and pneumatic line fittings and forged engine mountings.

Hungary flag 

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Ion vapour deposition; another name for  Ivadizing.

Hungary flag IVD

K

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The aspect of achieving coating adherence through mechanical interlocking.  A surface maybe deliberatley roughened, for example, via grit blasting, to achieve this effect.

Hungary flag bekapcsolás

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A method of microindentation hardness also termed toucan indentation hardness.   The  diamond indenter has a diamond shaped pyramid, with one apex (along the major axis) at 172.5°and the other (along the minor axis) at 130°.   Knoop hardness is given by the equation:

HK = 2P/L2 (cot 172.5° + tan 130°) = kg/mm2

or  HK = 14.23 P/L2 = kg/mm2

where L is the long diagonal length and P is the load in kg.

Hungary flag Knoop keménység

L

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A laser is a device which achieves a finely controlled emission of coherent, monochromatic high energy radiation ranging from the ultra-violet to the infra-red wavelength range.   The most common medium in which the lasing action can be created are gases of various compositions; in surface engineering the CO­2 laser is the most popular.   The gas used comprises a mixture of 10% CO2 , 30% N2 and 60% He which  is rapidly circulated at reduced pressure between two pairs of electrodes which results in the generation of an electrical discharge and excitation of CO2 molecules;  when the excited electrons fall return to their lower energy levels photons are emitted which stimulate further photon emissions (from adjacent molecules) which are perfectly in phase and of the same wavelength (10.6 µm for CO2 molecules).    This emergent laser light has high phase contrast, can be focused to very small diameters, approximatling to the wavelength of laser light, which enables high power densities (≈103 to 1010 W/cm2) to be realised.    When coupled with appropriate substrate and/or laser beam manipulation, a wide range of interaction time, from 1 to 10-8 seconds can be obtained (diagram).  

Hungary flag lézer

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The surface zone whose composition has been modified by laser alloying.  Typically between 20 µm and 1.00 mm deep.

Hungary flag Lézer ötvözte zóna (LAZ)

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Laser treatment applied to a metallic surface which is momentarily surface melted to enable the encapsulation of preplaced or injected ceramic powder particles.   The treatment is applicable to ferrous or non-ferrous metals and alloys.  There has been a lot of interest in recent years in applying such treatments to aluminium and titanium alloys because both of these suffer from the disadvantage of responding poorly to thermochemical diffusion treatments, i.e., they develop very shallow treatments, if any.   Laser cladding offers the possibility to develop deeply hardened surfaces, up to 1 mm.  The process is analogous to electron beam cladding.

Hungary flag Lézeres bevonatolás

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A vacuum evaporation (PVD) method in which a laser beam is scanned over the surface of a solid source or target, causing evaporation through laser ablation.   The laser beam is passed through glass port in the vacuum chamber.   The process can be carried out under high vacuum conditions (≈10-6 Torr) when the substrate remains at near ambient temperature, or the substrates may be negatively biased in an appropriate atmosphere (e.g., Ar) held at ≈10-2 torr which creates a glow discharge plasma, providing substrate heating (to temperatures ≈400°C) and improving throwing power.     One advantage of using a laser is that electrically insulating materials can be evaporated; this is less easy with the more usual electron beam methods.

Hungary flag Lézeres elpárologtatás

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Also termed laser vitrification.   Achieved by surface melting with a laser beam at power densities ≈ 105 to 107 W/cm2 for  ≈ 10-3 to 10-7 seconds; cooling rates exceeding 105 K/s can be realised which suppress the usual nucleation and crystallisation processes that accompany solidification.   Instead,  amorphous or vitrified (glass) surface layers are produced.   The Nd-YAG or Excimer lasers are especially suited for laser glazing.     The latter has recently been demonstrated to improve the statistics  of  fracture (i.e., the Weibull modulus) of Al2O3 ceramics by healing surface defects.   This represents a significant break-through in materials processing.

Hungary flag zománcozás

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Any laser treatment which results in hardening, in the absence of externally applied alloying elements or second phase particles.   Hardening often results from the rapid solidification following laser melting, i.e., due to the creation of a very fine dendritic microstructure.  In some cases crystallisation is suppressed and a hard glass is produced (laser glazing).  Laser hardening can also be produced by manipulation of solid state transformations; see laser transformation hardening.

Hungary flag Lézeres keményítés

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Any surface modification resulting from the action of laser beam heating.

Hungary flag Lézeres hőkezelés

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Any laser assisted process.   A very broad term encompassing laser heat treatment, laser welding and laser cutting.

Hungary flag Lézeres eljárás

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Any surface modification resulting from the action of laser beam heating.

Hungary flag Lézeres felületkezelés

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A process applied to ferrous alloys with >0.35wt-%carbon.   Laser power density  (≈103 to 104 W/cm2) and interaction times (≈10-2 to 1 s) are adjusted to cause rapid austenitisation of the surface; the heated zone subsequently self-quenches by conductive heat loss into the steel core beneath (water quenching is not required) which remains at ambient temperature.  The resulting martensitic case can be furnace tempered, but this is not usually practised.   The process produces less distortion than, for example, induction hardening, since only a very small volume of the object is heat treated.

Hungary flag Lézer transzformációs keményítés

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Any laser assisted process.   A very broad term encompassing laser heat treatment, laser welding and laser cutting.

Hungary flag Lézeres kezelés

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There are three "Laws of Sliding Friction".   Although the first two have been attributed to Amontons (1699), Leonardo da Vinci  described them much earlier (circa 1500).    The third law is attributed to Coloumb (1785).   The laws are:

(i) the friction force is directly proportional to the normal force

(ii) the friction force is independent of the apparent sliding contact area

(iii) the friction force is independent of sliding speed

It should be noted that polymers do not follow the first two laws because of their tendancy to flow plastically at their surfaces and to undergo localised asperity welding (seizure or adhesion) even under very low contact loads.

Hungary flag Surlódási törvények

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Any multi-layered coating.

Hungary flag Többrétegű bevonatolás

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Carburising restricted to certain parts of a surface.   Best achieved by induction hardening  or laser transfromation hardening.  However, paste carburising  can achieve similar results.

Hungary flag Lokalizált karbonizáció

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Any fluid that serves to provide lubrication between solid sliding surfaces.   Mineral oils of varying viscosity and additive content presently constitute the majority of lubricants used in, for example, automotive engines.   The safe operating range of such oils is schematically presented (adapted from R. G. Baker, "Bearings in the automobile - a challenge for the materials engineer", Metals and Materials, 1, (1), pp 45-52, 1985).   Additives, like boundary lubricants and anti-oxidants, are used to broaden the operational range of such oils.

Hungary flag Kenő anyag

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A method of lowering the coefficient of friction between two sliding surfaces, achieved by separating them with: (i) a liquid lubricant (e.g., a mineral oil) and/or; (ii) a dry lubricous coating (e.g., molybdenum disulphide or lead).   Also see boundary lubrication, hydrodynamic lubrication  andelastohydrodynamic lubrication.

Hungary flag Kenés

M

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A diagram depicting the operational cutting speed and feed rate ranges of a specific tool material used for turn-cutting a specific workpiece material.   The diagram indicates operational stability ranges for various types of chip morphology, e.g., built-up-edge and continuous chip forms together with the dominant tool wear mechanisms.   Such diagrams were originally conceived by Trent (circa 1965) and were originally worked out for cemented carbide type cutting tool materials.       Such charts provide a practical guide-line for the optimal operating ranges of various tools.  the diagram depicted below is for a steel cutting grade cemented carbide used on suatenitic stainless steel.   The optimal range resides between the shaded zones.  At low speed where built-up-edge forms, carbide tools fail rapidly through a process of attrition.  At higher speeds, failure is caused through plastic deformation of the cutting edge.    Similar regimes exist for other workpiece materials, but the precise cutting speeds and feed rates differ significantly; this is due to widely differing variations in tool temperatures and stresses when cutting dissimilar materials.

Hungary flag Megmunkálási diagram

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A high rate sputter deposition (plasma assisted PVD) method.   A tunnel shaped magnetic field is created in front of the target face;  this serves to trap the available electrons in tightly defined orbits.    The number of electron-atom and electron-molecule collisions in front of the target face is increased resulting in the creation of a high ion concentration.   Hence, for a given pressure, more ions are available for sputtering through ionic bombardment than for a non-magnetron cathode;  there is a marked increase in sputter yield and deposition rate.   The following table shows that an order of magnitude increase in deposition rate is possible with magnetron enhancement.

Hungary flag Megnetronos bevonatolás

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The four states of matter used to transfer mass, i.e., solids, liquids, gases and plasmas.  In surface engineering these usually refer to pack, salt-bath, gaseous and plasma assisted methods.

Hungary flag Halmazállapot változtató közeg

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Any process that renders surface cleaning by mechanical action.

Hungary flag Mechanikai tisztítás

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A method of coating whereby a combination of mechanical and chemical action is used to produce a coating from powdered metal.   The process is carried out in a ball mill.  Also called peen plating.

Hungary flag Mechanikai bevonás

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Polishing performed by pressing a surface against a revolving soft wheel impreganted with fine (<10 µm) abrasive particles such as daiamond or Al2O3.

Hungary flag Mechanikai polírozás

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A general term embracing the treatments aimed at modifying the properties of the surface of an object using static or dynamic mechanical action.  The main types of mechanical surface engineering are: shot peening, mechanical plating, surface rolling, hammering and friction surfacing.

Hungary flag Mechanikai felülettechnológia

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A paint containing metal powder.  For example, aluminium powder is used to impart moderate corrosion protection for ferrous surfaces while paints containing copper or gold particles are used for decorative purposes.

Hungary flag Fémes festés

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See diffusion metallizing.    Also sometimes meaning those thermal spraying methods used for producing metallic coatings.

Hungary flag diffuziós fémbevonás, fémleválasztás

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The temperature at which austenite has completely decomposed to martensite.

Hungary flag Mf hőmérséklet

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See chromium plating

Hungary flag Mikro-repedéses krómozás

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Hardness measured using diamond pyramide indenters (Vickers or Knoop method) at loads ranging from 2 g to 2 kg.  Also see hardness profile, Berkovich hardness, Vickers hardness  and Knoop hardness.

Hungary flag Mikro-keménység

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A thin coating (<20µm) comprising alternating layers of two or more distinctly different metals or ceramics, deposited by, for example, one of the plasma assisted PVD methods.  The variation in composition is typically sinusoidal; hence, for a duplex variant,  it is feasible to classify the coating in terms of a compositional wavelength, which can be as small as 10 nm.  Also see superlattice coatings.

Hungary flag Szaggatott bevonat

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The temperature at which austenite commences decomposition to martensite.

Hungary flag Ms hőmérséklet

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Thermochemical treatment involving the enrichment of the surface layer of an object simultaneously or consecutively with more than one element.

Hungary flag Sokösszetevőjű termokémiai kezelés

N

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A recent method of microhardness or ultramicrohardness using very small indentation loads ≈10µN to 5mN in conjunction with a Berkovich (triangular base pyramid) diamond indenter.   Machines record the penetration depth as a functin of indenter displacement.  The technique is able to determine the hardness of very thin coatings (<1µm thick); from the slope of the load-unload curves elastic moduli can also be derived.   A disadvantage of technique is its high sensitivity to sample surface roughness.

Hungary flag Nano-benyómódás keménység

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A solid-state laser in which an yttrium-aluminium-garnet (YAG) crystal, doped with neodymium (Nd) ions, constitutes the laser active medium.  With this laser it is possible to achieve laser pulses of a very short duration (several ns) each being of extremely high power (up to 1 GW).   Hence, this laser is ideally suited for laser glazing.

Hungary flag Nd-YAG lézer

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An electroplating process in which nickel is deposited from a Watts, sulphamate or fluoborate bath.  Nickel electroplating is applied for corrosion protection, primarily to steel but also brass and zinc.  To a minor degree it is also used for decorative purposes.   Also see electroless nickel plating.

Hungary flag nikkelezés

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The ability of a material, usually a steel, to increase its surface hardness by the solution of nitrogen.   For steels, it is essential they contain elements that develop coherent nitride precipitates during nitriding.  Typically, these elements are Cr, Mo, Ti, V and Al.   Nitridability also refers to the rate of nitride case development.    A steel of high nitridability is one which develops a nitrided case of significant thickness, at a given temperature, after a relatively short time.

Hungary flag Nitridálási képesség

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Thermochemical diffusion treatment involving the enrichment of a metallic surface with nitrogen.  Plasma, gaseous and salt bath media can be used.   Due to its dependence on cyanide based salts, the latter is now less widely practised.

Hungary flag Nitridálás

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Low alloy steels typically containing ≈0.25 wt-%C and 3.0 wt-% Cr with minor additions of molybdenum (≈0.50 wt%).   Among the most popular types of nickel-chromium-molybdenum steels are BS970:722M24.  Chromium can be reduced and replaced by aluminium.   This serves to enable higher prior tempering tempertures, without impairing nitridability. (Note: chromium carbide precipitation is significant on tempering above 550°C; such chromium is not able to participate in subsequent nitriding reactions.   Hence the virtue of aluminium bearing steels like BS970:905M31.) 

Hungary flag Nitridáló acélok

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A thermochemical diffusion treatment applied to plain carbon steels whilst in the ferritic state.  Nitrogen (the major solute) and carbon (the minor solute) are simultaneously diffused into the steel surface at temperatures ≈550-590°C for times that are typically less than 3 hours.   The treatment produces an external compound layer comprising mainly e-Fe2-3N although some g'-Fe4N may also exist as a minor constituent.  Small increases in fatigue strength and endurance can be achieved by developing compressive residual stresses in the diffusion zone beneath the compound layer.  This is achieved by  quenching the components into water or an oil/water emulsion after completion of the diffusion stage.     Although first popularised as a cyanide based salt-bath technique, environmental legislation has lead to significant developments in gaseous (see Nitrotec and NitrotecS ) and plasma nitrocarburising methods.   These are now replacing salt bath methods.

Hungary flag cementálás

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Variation in nitrogen distribution as a function of depth below the surface.

Hungary flag Nitrogén eloszlás

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Any coating that inhibits sticking or fouling by solids or suspended solids.    Apart from obvious domestic applications, such coatings are often applied to the internal surfaces of pipes used in the dairy and food processing industries for the conveyance of food products.   Sometimes known as "release coatings".    Also see PTFE coating.

Hungary flag Nem-ragadó bevonat

O

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The property of some coatings not to transmit rays of a specified wavelength, e.g., the ability to absorb radio waves (radio-opaque).

Hungary flag Fedőképesség

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Coatings developed for enhancing the optical properties of glass.    Such properties include refractive index, infra-red absorbtion and reflectance.  The most common coating materials are vanadium oxide, aluminium oxide, tantalum oxide, silicon dioxide and silicon oxynitride.  These maybe applied singly or as multi-layered, multi-phased coatings, usually using RF plasma assisted PVD or CVD methods.

Hungary flag Optikai bevonatok

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Properties of a coating material which characterize its behaviour in relation to the electromagnetic radiation of the optical range (i.e. visible, infrared and ultraviolet) incident upon it (e.g. reflectance, transmittance, index of refraction).

Hungary flag Optikai jellemzők

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Any coating deposited without chemical reaction with the substrate.

Hungary flag Nem kémiai eljárással készült bevonat

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Thermochemical diffusion treatment in which oxygen is deliberately introduced into the surface layer of an object.  The process is carried out in a controlled atmosphere, or air vented furnace.   Some recent innovations in this area have been the thermal oxidation of zirconium which results in an external layer of zirconia which is highly wear resistant; further it is mechanically supported by a zone of oxygen solutionised zirconium beneath, making it tolerant to point contact loads.  This material is presently being investigated for use in the bearing surfaces of orthopaedic implant materials, e.g.,  by Smith & Nephew Richards of Memphis, USA.  Also see steam treatment  and the nitrotec  group of processes where selective oxidation plays an important role.

Hungary flag Oxidáció

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The ability of a material to withstand degradation by oxidizing atmospheres, e.g., as found in gas turbine applications.

Hungary flag Oxidációval szembeni ellenállólépesség

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A process observed in rolling or sliding contacts whereby oxygen ingresses the contacting surfaces leading to localised oxidation.   The process is stimulated by the ocurance of "hot-spots".   The oxide grows to a critical thickness beyond which it is sheared off and removed.   The kinetics of such dynamic oxidation are generally agreed to be more rapid than for static oxidation.   Many oxidational wear models exist, but the principal theory is attributed to Quinn.    For example, see T. F. J. Quinn, Wear, 1992, 153, 179-200.

Hungary flag Oxidációs kopás

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Thermochemical treatment involving the diffusional enrichment of a ferrous surface with nitrogen and oxygen.  Oxynitriding has been applied to metal cutting tools made from high-speed steel.   The process increases surface hardness;  it is claimed that wear resistance is also improved.     However, this is likely to be at the expense of toughness - a similar scenario takes place after nitriding high speed steel.      Oxynitriding can be conducted at temperatures ≈520-560°C for 0.5-2 hours in a gaseous medium of ammonia and water vapour.  The depth of the treated zone is in the range of 10 to 60 µm.

Hungary flag Nitrogén-oxigén eljárás

P

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Maybe carried out using 100% hard wood charcoal, but more often, the commercal carburising pack compositions comprise 6 to 20wt-% activating compounds bound to hard wood charcoal and/or coke by molasses, tar or oil.   Barium carbonate has been a principal activator; due to its toxicity this is being discontinued in the United States because of industrial control legislation.  Calcium, sodium and potassium carbonates are suitable alternatives.   The activator(s) serve to create carbon dioxide via the reaction:  

CaCO3  --> CaO +  CO2

which then reacts with the charcoal/coke:

 CO2  + C <==> 2 CO

The CO is then reduced to carbon at the steel surface where it is dissolved in the austenitic phase:-

Hungary flag szilárd közegben, ládában cementálás

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(i) an obsolete term for pack carburising; (ii) Any pack method that results in the diffusional formation of a surface layer (or layers) enriched in interstitial or intermetallic compounds.   Such processes include, pack boriding, pack aluminising and pack chromising.   All these processes involve embedding components within a powdered pack contained inside a vessel, which is then placed inside a furnace.    Sometimes inert or reducing gases are passed through the pack (e.g., pack aluminising and pack chromising) in other cases no external gases are required (e.g., pack boriding).    Process control is difficult with such techniques, especially with regard to controlling the activity or potential of the diffusiong specie(s).   Pack constituents may be costly and are often used several times.   After each diffusion cycle the powders become depleted in constituents and their activity or potential reduced.    Industrial users therefore implement methods of "topping-up" powders with new constituents.   This calls for stringent management of the powders.   A detailed knowledge of the effect of various substrate compositions on pack life must also be accumulated. Also see minor thermochemical diffusion techniques.

Hungary flag szilárd közegben cementálás

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Carried out by embedding components in a mixture of powders comprising, Al, Cr, Cr2O3 (the sources of Al and Cr) and NH4Cl. (the activator).  The process is conducted at temperatures ≈950-1100°C for 2-4 hours.  The thickness of the layer produced does not exceed 100 µm.

Hungary flag szilárd közegben krómaluminizáció

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Conventional packs comprise a mixture of chromium metal or ferrochromium powder and an an activator such as NH4Cl, NH4Br or NH4I.  A gas tight container is required and hydrogen is passed through the pack which is heated between 850 and 1050°C for up to 12 hours.   In a more recent development, components are packed in a mixture of FeCl3 and metallic chromium powders, which on heating react to produce (probably) CrCl2; argon or nitrogen is passed through the pack to prevent ingress of oxygen.  CrCl2 is reduced to Cr at the surface of the steel components.  In both cases chromium diffuses into the steel and produces a surface layer whose constitution depends upon the steel substrate composition (see: Chromising ).

Hungary flag szilárd közegben krómozás

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Sherardizing is carried out in a powdered medium consisting, as a rule, of zinc powder or dust with additions of zinc chloride or ammonium chloride to provide activation.   Sometimes an inert substance (e.g. aluminium oxide, fireclay or high-silica sand) is added to act as a diluent and prevent sintering togther of the zinc particles.  Temperatures ≈400-800°C for 2-4 hours are typical.  The process can be further assisted by rotation of the charge (tumbling).  The thickness of the diffusion layer is  ≈ 30 to 200 µm.     Also see sheradizing.

Hungary flag szilárd közegben horganyzás

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Siliconising carried out by embedding components in a powdered mixture comprising silicon mixed with silicon carbide, silico-calcium or ferrosilicon.   The diluent is usually  alumina or magnesium oxide, while NH4Cl, NH4I, NH4F, KF or NaF act as the activator phase.  The process requires ≈4-6 hours at 950 to 1200°C. 

Hungary flag szilárd közegben szilikonizálás

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An electroplating process in which palladium is deposited from tetra-amino palladium nitrate solutions, which contains ≈10-15g/l of palladium. The process uses platinum or platinised titanium anodes. Typical coating thicknesses are in the range of 2 to 5 µm.   Palladium plating is used as a substitute for gold or rhodium plating, especially in the finishing of copper electrical contacts on circuit boards.   It has a Vickers hardness of 200-300 kg/mm2 which is higher than that of electroplated gold; hence palladium plating imparts reasonable wear resistance.     It also finds use for the high temperature oxidation protection of refractory metals, such as tantalum and molybdenum

Hungary flag Palládiumozás

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See vacuum carburising

Hungary flag vákuum cementálás

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See closed loop partial-pressure control..

Hungary flag atmoszférikusnál kisebb nyomás ellenőrzés

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Any vacuum deposition process whereby one of the constituents of the final coating is vapourised or atomised from the solid state within the vacuum chamber, prior to deposition.  The two methods of vapourisation/atomisation are evaporation and sputtering.   In general plasma assisted processes like ion plating can be regarded as PVD, but for these cases a more exact definition is plasma assisted PVD. 

Hungary flag Fizikai gőz bevonatolás

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A simple method of wear testing whereby a loaded pin slides against the face of a rotating disc under dry or lubricated conditions.  Pin and/or disc wear maybe monitored.  The US standard is ASTM G99.

Hungary flag 

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Localised, but deeply penetrating, corrosion of a surface.

Hungary flag Pontkorrózió

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Particle induced X-ray emission; also sometimes called proton (H+) induced X-ray emission.   A very high energy (0.5-4.0 MeV) particle (usually H+ or 4He+) beam is directed normal to the sample surface.   The ions collide with the lattice atoms of the sample.    Some are back-scattered (see RBS ) or trigger nuclear reactions (see NRS ) while others cause K-shell ionisation, excitation and X-ray emission.  The X-ray production cross section (ska) is related to the ionisation cross section (s) through the fluorescence yield (wx) according to the equation:

ska = s. wx

The power input of induction coils lies in the range of 0.1 to 2.0 kW/cm2.  Choice of frequency depends upon the depth of treatment required per second of interaction time.   Simplified relationships exist to enable calculation of the approximate depth of the heat affected zone (dh) for steel up to the hardening temperature.   For example, at 800°C;  dh ≈ 100/√ƒ, where ƒ is the induction frequency in Hz.   Hence, high frequencies ≈ 250 k.Hz are used where shallow treatments ≈ 0.2 mm are required, while low frequencies ≈ 4 k.Hz are used where deeper treatments ≈ 1.6 mm are required.   Induction coil diameter and the number of turns in a particular coil, are also of importance.   Also see flame hardening.

Hungary flag Részecske indukált röntgen sugár emisszió

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See glow discharge plasma  and radio frequency glow discharge.

Hungary flag plazma

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Any process that utilises a glow discharge for the mass transfer of elements to a component surface. Such processes take several hours to complete to enable diffusion of the transported elements into the substrate.  

Hungary flag Plazma diffúziós módszerek

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A term encompassing all plasma diffusion methods and any annealing or hardening treatments where heat is provided (at least in part) by a glow discharge plasma.

Hungary flag Plazmás hőkezelés

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Also sometimes called plasma source ion implantation (PSII).  A near non-directional method of ion implantation.   A low power (≈1 kW) radio frequency (RF) plasma (e.g., 13.56 M.Hz) is used to provide nitrogen ions which are accelerated towards test-pieces or components held at very high negative potential.  The ions impact the surface with energies ranging from 20 to 200 keV.   Since there is presently an interest in applying this treatment for improved wear resistance of steels, greater treatment depths are being produced by using higher treatment temperatures (≈300-400°C) than used for conventional ion implantation.  This necessitates the use of radiant heaters.   Treatment depths up to 100µm can be achieved in this way.  The process can be regarded as a form of nitriding, although quantification of the nitrogen potential remains a challenge.  PI3 is being developed at several research institutes throughout the world and its industrial viability has yet to be demonstrated.    Its process economics will require close scrutiny in comparison with plasma nitriding.

Hungary flag Plazmás ion beültetés (PI3)

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A thermal spraying process in which the coating material, in the form of powder, is introduced into a high enthalpy plasma torch, melted and propelled onto the surface of a component (particle velocities ≈ 150 m/s), which maybe typically ≈200 to 500 mm away from the torch exit.   Both dc and RF plasma torches can be used; dc torches are more established.   The process can be carried out in air at atmospheric pressure (here the technique is termed air plasma spraying (APS)) or at sub-atmospheric pressure in the presence of a protective atmosphere (see vacuum plasma spraying ).  It is a "line-of sight" process and works best on external surfaces.  Special designs of plasma torch are available which enable spray coating of internal surfaces, but these are generally confined to relatively large ≥50 mm diameter bores.

Enthalpy of the plasma torch is controlled by (i) changing the inter-electrode current; (ii) selection of the plasma supply gases.   Diatomic gases, especially hydrogen and nitrogen, produce a higher enthalpy plasma torch than monotomic gases like argon and helium.  Accordingly, plasma torch temperatures vary considerably;  temperatures ≈12000 K are easily attained.    The creation of sound coatings, containing minimal porosity, is dependent upon achieving a high efficiency of powder melting.   Hence, for high melting point ceramic powders, like alumina (Al2O3) and zirconia (ZrO2), a high enthalpy hydrogen-argon gas mixture is required.   The selection of a very high enthalpy plasma has to be balanced by the need to obtain satisfactory electrode life; this diminishes as the enthalpy of the plasma increases.  Electrodes are usually made from thoria dispersed tungsten and are a significant cost factor.

Hungary flag Plazma szórás

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Usually referring to any metallic coating produced by electroplating.

Hungary flag Lemezelés

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A standard method of quantifying the preferred crystallographic orientations of bulk and surface modified materials by measuring the intensity of X-rays diffracted from a surface for a specific diffraction condition, using an X-ray pole figure goniometer.   For example, the intensity of X-rays diffrcated by the {111} planes of a TiN coating can be measured over a complete range of angles from the surface  normal (90°) to about 5° above the sample surface.  Examples of the pole figures of TiN coatings, deposited by two different methods,  are given in the citation for texture.   Although three pole figures are usually required to provide a complete description of crystallographic texture, one pole figure is considered adequate for fibre textured coatings or materials.

Hungary flag Pólusábrák

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Porosity frequently occurs in surface engineered materials, epecially in thermal sprayed coatings.  Poor selection of power beam paramaters can also cause porosity to occur in power beam surface alloyed or melted surfaces.   Sometimes, porous surfaces are deliberately encouraged, e.g., in the Nitrotec  process, micropores are developed in the compound layer which serve to retain wax for the purpose of imparting corrosion resistance.   Also see coating porosity   and laser healing.

Hungary flag Porozitás

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Any thermal spraying method in which a metallic material is deposited

Hungary flag Porkohászat

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Any treatment involving localised liquid-phase alloying of (usually) metallic surfaces.  A high power density beam (laser or electron) provides the thermal energy required for melting; in the case of laser treatments oxidation protection is provided by a He gas shroud, electron beams are operated in-vacuo.   Alloying elements can be injected into the molten pool as a powder (termed "particle injection") or as a gas (e.g., laser nitriding or electron beam gas alloying); alternatively, a solid coating can be pre-placed on the metallic component and subsequently "melted-in".   The latter provides better control with respect to the amount of material

being alloyed.   Such techniques are highly "line-of-sight" and are most easily applied to external surfaces.  

Hungary flag nagyteljesitményű lézeres felületötvözés
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Commonly expressed in W/cm2.   This parameter is of great importance in plasma, laser and electron beam methods of surface engineering. 

Hungary flag teljesítménysűrűség

R

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Rutherford backscattering spectrometry.   This method requires a very high energy (0.5-4.0 MeV) particle (H+, D+, 3He+,4He+) beam which is directed normal to the sample surface.   The ions collide elastically with the lattice atoms of the sample.   Many are back-scattered and subsequently collected by a detector which counts their number and measures their energy.   It is an important faeture of RBS that the energy of the back-scattered particles  can be used as a basis to calculate the depth and/or mass of the sample atoms that caused the scattering.   During RBS the amplified detector signal is collected over a period of time by a multi-channel analyser.   The "raw data" is subsequently displayed as yield (proportional to the total number of back-scattered particles) against channel number (proportional to energy).   These results are then quantified with well proven computer simulation programs (e.g., see J. C. B. Simpson and L. G. Earwaker, Vacuum, 1984, 34, 899), which through iterative calculation enables the derivation of depth concentration profiles.   RBS is particularly suited to determining concentrations of high atomic number elements dispersed in a low atomic number matrix.       The maximum useful detection depth (below the surface) is about ≈1 µm.   Also see NRA.

Hungary flag RBS

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Any atmosphere which reacts with a surface or that combines with other species to form a surface coating or diffusion zone.  For example, controlled reactive atmospheres form the basis of gaseous nitriding, gaseous carburising, reactive ion plating and reactive sputter deposition.

Hungary flag Reagens atmoszféra

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Any medium which reacts with a surface or that combines with other species to form a surface coating or diffusion zone.  Controlled reactive media form the basis of many techniques, especially  thermochemical diffusion and deposition methods.

Hungary flag Reagáló közeg

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Any sputtering method whereby multicomponent coatings, such as interstitial compounds, can be produced by sputtering into a reactive atmosphere, e.g., transition metals can be sputtered into nitrogen or carbonacous enriched atmospheres to produce, respectively,  transition metal nitrides (diagram) or carbides according to the following generalised equations (where M equates to the metal component):

2M + N2 --> 2MN

M + CH4 --> MC + 2H2

Reactive sputtering is deployed in both magnetron and non-magnetron sputtering modes of operation.   The former is preferred because of its higher deposition rate.   See magnetron sputtering.

Hungary flag reakcióképes katódporlasztás

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Residual elastic stress (actually strain) within a material; subdivided into macrostress and microstress.    Macrostress is residual elastic stress (strain) that occurs in a very large number of grains and is transmitted across adjacent grain boundaries.    Microstress is elastic stress (strain) confined to individual grains that is not transmitted across adjacent grain boundaries.    Both types of stress are best measured using x-ray diffraction methods.   Macrostress is determined from the peak shift observed when an object (sample) is rotated through j (the angle between the plane normal and the surface normal) while fixed in a specific diffraction condition (i.e.,  at a specific 2q value); a plot of sin2j versus  (dj-d0)/d0 is obtained, where d0 is the unstrained d-spacing and dj,the strained d-spacing at a surface angular rotation of j.  The slope of this plot is used to calculate the residual macrostress,  provided Young's modulus (E) and poissons ratio for the material under investigation is known.     Microstress is determined from a numerical analysis of the peak broadening observed at very high angles of 2q.    Other methods of quantifying residual stress also exist; these encompass ultrasound, neutron diffraction, microdrilling and magnetic field techniques.

Hungary flag Belső feszültség

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 Moderate quantities of retained austenite are unavoidable in carburised cases.  When retained austenite exceeds ≈ 50 vol% there is a marked reduction in case hardness and fatigue strength (rolling contact and rotation-bending).   The usual cause of excessive retained austenite is a too much case carbon (> 0.9wt-%) caused by a too high carbon potential.   Retained austenite is always most noticable at component corners, where, during carburising,  carbon is being supplied via two faces.  In the worst examples, massive, blocky iron carbides can from at the corners.   The quantification of retained austenite is best achieved by using an x-ray diffraction procedure.  Commonly the ratio of the intensities of the {200}a' to that of the {111}g are used for this purpose.

Hungary flag maradék ausztenit

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A method of hardening surfaces through localised cold working.  In the case of cylinderical objects, the surface is pressed between three rolls, which are rotated over the surface, while applying sufficient pressure to cause plastic deformation.  The cold worked surface remains in a state of residual compressive stress,  imparting a marked increase in fatigue strength.   This technique is applied to high strength steel, nickel and titanium alloy bolts.  High strength bolts, used for securing engine heads, are often strengthened below the bolt head using roll hardening; it is very effective in preventing dangerous fatigue failures.   For a practical review of this technology,  see: G. Turlach, Surf. Eng., 1985, 1, 17-22.

Hungary flag Felületkeményítés hengerléssel

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An effect that takes place by the conjoint action of rolling contact and traction stresses as typified in the operation of gears, i.e., where there is continous contact between two surface moving at slightly (≈10%) dissimilar surface speeds.    Nitriding and carburising are probably the two most important surface engineering methods that markedly improve the rolling contact fatigue endurance of steels.  The diagram (based on data from M. Weck and K. Schlotermann, Metallurgia, 1984, No 8,  328-332) shows the effectiveness of plasma nitriding in raising the fatigue strength and endurance of gear teeth made from prior hardened and tempered low alloy steels (designated DIN 31CrMoV9V and 16MnCr5N); note: the nitrided case depth is given in parentheses.    The plain carbon steel (DIN CK45), containing no nitride forming elements, has a fatigue strength and endurance only slightly better than an untreated steel;  hence, this material was in the nitrocarburised state and had an outer surface layer of e-carbide, several micrometers thick.  

Hungary flag Hengerlési kifáradás

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In the case of untreated steel surfaces, rolling contact fatigue stresses result in the formation of localised surface failures, which result in cavities ≈ 20 to 100 µm across, being formed.      For treated (carburised or nitrided) or untreated steels, superficial surface plastic deformation can also take place.   In the absence of an oil based lubricant, mild or severe oxidational wear also contributes to the overall wear.

Hungary flag kopás

S

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A term first coined by Ichii and others to describe the shallow (≈3 µm) surface zone produced in the absence of CrN after nitriding austenitic stainless steels at or below 500°C.   The precise nature of S-phase has yet to be conclusively elucidated, but it is characterised by exceptional hardness (≈1300 kg/mm2), high residual stress and outstanding corrosion resistance.   It displays only three or four broadened diffraction peaks when exposed to monochromatic X-rays;  the peak positions being consistent with a tetragonal unit cell.     The phase is meta-stable; it is not observed when  nitriding at ≥550°C.   Instead, the chromium is partitioned out of solution as CrN.   In plasma nitriding, relatively high power densities are required to induce the formation of S-phase.    Also there have been some practical experience with lack of uniformity of treatment, especially when treating large numbers of components.   The diagram shows potentiodynamic sweeps (at 0.5 mV per second) for AISI 316 austenitic stainless steel plasma nitrided in cracked NH­3 for various temperatures and times, e.g., 800/10 indicates 800°C for 10 hours.  All tests were carried out in 3% NaCl solution at ambient temperature relative to a Standard Calomel Electrode.  The data shows that all samples containing S-phase (500/10, 500/36 and 450/36) have superior corrosion resistance to non-nitrided AISI 316.   Samples nitrided at 600°C and above (where CrN predominantly forms) exhibit inferior corrosion resistance.      Data from P. A. Dearnley,  A. Namvar, G. G. A. Hibberd and T. Bell, Proc.Plasma Surface Engineering,  Vol. 1, 219-226, 1989, Oberursel,  DGM.

Hungary flag S-fázis

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A standard microscopy method with exceptional depth of field.   Modern instruments now deploy field emission electron sources which provide excellent illumination.   Especially useful for the examination of worn, corroded or fractured surfaces

Hungary flag Pásztázó elektronmikroszkópia

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A relatively new technique enabling the resolution of lattice points on a sample surface. The method may prove useful in the elucidation of wear and corrosion mechanisms.

Hungary flag Pásztázó alagútmikroszkópia

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A test where a diamond stylus is dragged over a surface.  The load on the stylus is progressively increased until the coating fails.   Some experimental set-ups enable the recording of acoustic emissions which aid interpretation of the recorded forces;  a large 'jump' in acoustic emission often accompanies coating failure.   Hence, the force required to cause coating failure is detected.   Also see adhesive (or adhesion) strength tests.

Hungary flag Karcolásos adhézió teszt

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When two formerly sliding surfaces bond or weld together.  In the case of metal on metal seizure, a metallurgical bond is made across the contacting interface.   Seizure can take place as a result of very high contact loads and/or when lubrication breaks down.    Some metals, like titanium and austenitic stainless steel show a greater tendancy to seize (for a given loading situation) than other materials.   Seizure may take place intermitently and culminates in localised fracture or tearing.  This latter phenonemon is sometimes termed galling or, less appropriately, scuffing.   When on a small scale,  the resulting wear is sometimes called adhesive wear.    In metal cutting a special situation arises where the metal chip or swarf is seized to the tool rake face over most of the contact area.   The chip does not slide over the tool surface but is intensely sheared within a narrow shear zone.   This results in the creation of sufficient heat to commonly raise the surface temperature of cutting tools to well over 900°C.

Hungary flag Beragadás /beszorulás

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Thermochemical diffusion treatment involving the enrichment of a metallic surface with zinc; carried out at temperatures ranging from 500 to 800°C for 2 to 4 hours.  The main use of sherardizing is to increase the corrosion resistance of components constructed from ferrous alloys, especially those exposed to rain and sea water.  The diffusion zone comprises various Fe-Zn intermetallic compounds, depending upon the exact thermal cycle deployed,  although, g-Fe5Zn21 is frequently the dominant phase produced by pack sherardizing and gaseous sherardizing.   No significant distinction can be made between what might be called liquid phase sheradizing and what is actually termed hot dip galvanising.    Processing temperatures for the latter method are somewhat lower than for pack sherardizing  and gaseous sherardizing.   Consequently, the diffusion layer differs in constitution, comprising several Fe-Zn intermetallic compounds (See hot dip galvanising ), not usually found in gaseous or pack sheradized surfaces.

Hungary flag Száraz horganyzás

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A laser surface hardening method that uses very high power densities ≈108 to 109 W/cm2 , with very short interaction times  ≈10-7 seconds, to vapourize a sacrificial overlay coating, and thereby impart shock-waves of such intensity to cause work hardening of the material beneath.   Rarely practised.

Hungary flag Sokk keményítés, edzés

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A mechanical surface engineering treatment in which the surface of a metal object is exposed to the action of a stream of hard metallic shot under controlled conditions.  This treatment results in increasing the hardness of the surface layer by cold working and inducing residual compressive stresses.  The main purpose of shot peening is to increase fatigue strength.   Great skill is required in the use of this technique.   If the peening intensity is too great, surface cracks result;  these can  have detrimental consequences.

Hungary flag sörétszórás

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Secondary ion mass spectrometry.   An incident ion beam of neutral or reactive character is directed at a solid surface causing the removal of surface ions (secondary ions) through sputtering. Although early SIMS instruments used low ion energies, <10KeV, it is now more common to use higher energies, ≈15 keV.     Argon is  a principal neutral ion beam, while oxygen and caesium are frequent reactive ion beams; secondary ions of either negative or positive polarity can be produced and SIMS instruments can be configured to detect either.  The secondary ions are collected by a mass spectrometer and quantified.   Under oxygen ion bombardment the positive secondary ion yield of electropositive elements, like Mg, V, Ti and Cr are at least three orders of magnitude greater than the positive secondary ion yields of electronegative elements like C, S and O.   Conversely when caesium ions are used and negative ions are detected, the reverse situation applies, i.e., the secondary ion yields of the electronegative elements are much higher than for the electropositive elements.   Regardless of polarity, the secondary-ion intensity IA* of a given element A, is related to its atomic concentration [A], viIA* = K.PA*.[A]

where K is a constant related to the ion beam density and PA* is the practical secondary ion yield of element A.  In practice K is difficult to determine.  However, if only the ratio of two elemental concentrations is sought (sputtered under similar conditions), then a knowledge of K is no longer required, since

Hungary flag SIMS

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The wear resistance of two component surfaces sliding over each other under lubricated, wet or dry conditions. 

Hungary flag Csúszás okozta kopással szembeni ellenállás

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Breaking away of surface fragments of material during wear.  Often invoked to mean flaking-off of a coating.   Also termed exfoliation.

Hungary flag Leválás

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A PVD process in which the atomization of coating material is achieved by sputtering, i.e. by bombarding the solid source (target) with ions and neutrals having high kinetic energy, so that the material is removed from the surface of the source by a momentum transfer process.  It is an inherently cooler process than evaporative PVD.  Furthermore, the avoidance of a molten pool facilitates the operation of the target in any orientation.  Without magnetron enhancement, deposition rates are typically lower than in evaporative PVD (see magnetron sputtering ).   Sputtering enables alloys and compounds to be readily deposited without deviation in composition.   Also see bias  sputter deposition    and unbalanced magnetron.

Hungary flag Fémbevonatolás

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A thermochemical treatment that produces a blue-black oxide on ferrous objects by exposing them to superheated steam.    It is  claimed to impart wear resistance and has been applied to high speed steels as a finishing treatment, although it results in inferior performance to PVD ceramic coated drills.    It also sometimes applied to highly polished steel to provide a decorative blue-black finish.   Also see blackening.

Hungary flag Gőzölés

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Also called masking.   A procedure for preventing surface treatment on a particular area of a component.      For the prevention of plasma nitriding or plasma carburising (of steel) a physical mask is usually used,  e.g, steel plugs serve to cover holes, while in the case of gaseous or vacuum carburising copper 'paste' is applied.    Electroplating masking procedures are detailed under selective plating.

Hungary flag Maszkolás

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The original component or testpiece material, which subsequently becomes modified by any given SE method, such as an appropriate diffusion, deposition or energy beam technique.

Hungary flag Erdeti komponens vagy anyag

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A variant of salt bath nitriding/nitrocarburising (circa 1947) in which sodium sulphite (Na2SO3) is added to the usual sodium cyanide/cyanate composition.  Although much initial confusion arose with respect to the role of the sulphur based compound, it is now regarded as mainly serving to activate the conversion of sodium cyanide (NaCN) to sodium cyanate (NaCNO), via the reaction:

Na2SO3  +  3NaCN  --> Na2S +  3NaCNO

Sodium cyanate is the active constituent in salt bath nitriding.

Hungary flag Sulfinuz

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The physical principle behind many surface engineering techniques.   This is achieved either through liquid state and solid state alloying.   The most common form of liquid state alloying is power beam surface alloying.   There are many treatments that utilise solid state alloying; these can involve: (i) interstitial diffusion, like, nitriding or carburising of steels or; (ii) substitutional diffusion, in the case of chromising  or aluminising steels.    Surface alloying enables a variety of surface properties to be developed to enable surfaces to better combat, corrosion, wear or rolling contact fatigue.

Hungary flag Felület ötvözés

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A term originally invoked by Bell and co-workers, circa 1983, to provide focus to the multi-disciplinary activities concerned with the science and technology of engineering surfaces.    Its main goal is to make possible the design and manufacture of materials with a combination of bulk and surface properties unobtainable in a single monolithic material.   The skill in surface engineering is to manipulate appropriate surface technologies to achieve optimal surface property designs, for specific applications, in the most cost effective manner.

Hungary flag Felület megmunkálás

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The chemical or mechanical processing step(s) which generate the final surface form of a component, e.g., finish turning or milling, diamond grinding and polishing.

Hungary flag Felület megmunkálás

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Any treatment that causes an increase in surface hardness.   Within the wider engineering community this term is frequently taken to mean induction hardening or carburising.

Hungary flag Felületkeményítés

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A term usually meaning a coating, but sometimes referring to a surface residue resulting from corrosion or wear, e.g., metal cutting tools often become coated with surface layers of manganese sulphide after cutting free machining (high sulphur) steels.

Hungary flag Felületi réteg

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Any change in surface composition or geometry achieved by any means.

Hungary flag Felület változtatás

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A surface preparation designed to roughen the surface prior to thermal spraying or elctrodeposition, to effect a mechanical 'keying-in' or mechanical inter-locking of the coating to the substrate.  Usually achieved through grit blasting.

Hungary flag Felület érdesítés

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A parameter determining the numerical surface roughness.   Measured, according to SI practice, as roughness average (Ra), although Centre-Line Average (CLA) and Arithmetic Average (AA) are terms still invoked by engineers in the English-speaking world.  A surface roughness trace is obtained by a talysurf or similar instrument.  For an idealised triangular surface roughness profile, Ra is 25% of the peak-to-valley height.   For a surface generated by a single point turning tool:

Ra = 0.25ƒ/(tan A + tan T)

Where ƒ = the feed rate; A= approach angle; T = trail angle

Hungary flag Felület érdesség

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Another term for weld hard facing  and any of the many thermal spraying  methods.

Hungary flag Esztergályozás

T

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In the examples of carburised or carbonitrided steel cases, tempering is a simple heat treatment conducted at 150-200°C to relieve some residual stress and impart sufficient toughness to obviate brittle fracture.

Hungary flag megeresztés

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The phenomenon of preferred crystallographic orientation (texture) often displayed by polycrystalline diffusion layers or surface coatings.   These are typically of fibre texture character.  The double-FCC TiN coating deposited by plasma assisted PVD methods,  frequently, but not always, has the majority of its crystals growing in the [111] direction, while TiN coatings produced by CVD, frequently, but not always, grow in the [220] direction.    Pole figures for these coatings are given below.  In both cases the TiN coatings were deposited onto "steel cutting grade" cemented carbide substrates, each depicting a classical fibre texture.   The intensity of the diffracted X-rays are expressed in "times random" units, where 1 times random equates to a randomly orineted sample.   LR and TR respectively refer to the longitudinal and transverse reference positions on the sample surface.  Many other surface treatments can produce similar effects, e.g., the orthorhombic h-Fe2Al5 phase, formed during hot dip aluminising of steel, predominantly grows in the [002] direction.  The practical implications of crystallograhic texture, for example, in regard to wear resistance, are of clear importance, but have yet to be convincingly investigated.  Texture is also sometimes referred to as preferred orientation.    Also see pole figure.  

Hungary flag Szövet

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A coating deposited onto components or structural elements exposed to high in-service temperature (e.g.. combustion chambers,  gas turbine blades and exhaust nozzles) with the aim of thermally insulating the substrate and protecting it from oxidation and/or sulphidation.    One such coating comprises two layers, namely of a creep resistant bond coat of nickel-cobalt-chromium-aluminium-yttrium alloy and an outer coating of stabilised ZrO2 or MgO.ZrO2 (magnesium zirconate).  Also see thermal shock resistance.

Hungary flag Hőgátló bevonat

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A general term covering many processes whereby a solid rod or powder of metal and/or ceramic is melted and propelled at an object or workpiece and resolidified.  The resulting coating or spray deposit is built-up as an array of overlapping splats of rapidly solidified metal and/or ceramic.   Thermal spray processes include; thermospraying, plasma spraying (APS and VPS), detonation gun spraying, HVAF, HVOF,  arc spraying  andwire spraying.

Hungary flag Hőráfúvás

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Immunity of a surface treatment to degradation by heat.   For exemple, carburised cases loose strength when receiving prolonged exposure to temperatures above 250°C, while nitrided cases only start to degrade at temperatures exceeding 350°C.  However, there many specialised coatings that have been designed to provide protection above 750°C, e.g., those used in gas turbines.  See thermal barrier coatings.

Hungary flag Hőstabilitás

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Any method of surface modification requiring heat and chemical action.  All diffusion methods fall into this catagory.   These can involve interstitial diffusion, as in carburising, nitriding and boriding,  or substitutional diffusion as in chromising and aluminising.  

Hungary flag Termokémiai kezelés

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One of the simplest forms of spray deposition, whereby powdered coating material is gravity fed or aspirated into an oxyacetylene flame.   For metal or alloy powders, particle melting is very inefficient and the resulting coatings can be very porous.  A number of special coatings have therefore been developed which undergo an exothermic reaction during their passage through the flame,  typical of these is the 82:18 nickel-aluminium powder.   This is a nickel powder that is coated with aluminium; it is not an alloy.   The aluminium initiates an exothermic (thermite-type) reaction during spraying resulting in a coating of higher density than otherwise possible.   Thermospraying is also used as the first step in laying down fusion hard facing alloys  by the spray and fuse process. 

Hungary flag termikus hőszórás

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A semi-schematic graphical depiction showing the influence of chamber pressure and homologous coating temperature (during deposition) on coating morphology.   The diagram is applicable to metallic or ceramic coatings produced by plasma assisted PVD and encompasses some of the morphologies originally reported by B. A. Movchan and A. V. Demchishin (Phys. Metal. Metallog., 1969, 28, (4), 83-90.) for Vacuum deposisted coatings produced at different homologous deposition temperature.     John Thornton discovered the existance of an additional morphological region "Zone T" (for sputter deposited coatings) and characterised the influence of deposition pressure on the stability of the morphological zones.   In general, it is preferable to produce most PVD coatings of the Zone T (fine-columnar) or Zone 2 (coarse-columnar) types; both are near fully dense.   PVD-ceramic coatings are invariably of these types when substrate temperatures are insufficient to produce the equi-axed Zone 3 type morphology.    Zone 1 coatings have a coarse-columnar morphology and contain significant levels of intergranular porosity and are to be avoided for most engineering purposes.   The diagram shown is adapted from J. A. Thornton, Ann. Rev. Mater. Sci., 1977, 7, 239-260.  

Hungary flag Thornton diagram

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A situation arising when (usually) hard particles are trapped between two counterfacing sliding surfaces moving in different directions.   A fluid (gas or liquid) may also be present.   The particles cause abrasive wear of the sliding surfaces.

Hungary flag 3-test elhasználódás

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One of the most common thin (≈5 µm) hard (≈2,000-3,000 Vickers) coatings applied to metal cutting and forming tools to convey wear resistance; usually applied by chemical vapour deposition (CVD).   Used most commonly as  one constituent of  a multi-layered, multi-phased coatings, as discussed in the comments  for titanium nitride coating.

Hungary flag Titán-karbid bevonat

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One of the most common thin (≈5 µm) hard (≈1800-2,500 Vickers) coatings applied to metal cutting and forming tools to convey wear resistance.   Depending upon the substrate material it can be deposited by Chemical Vapour Deposition (CVD) or one of the plasma assisted physical vapour deposition (PVD) methods.   It has moderate oxidation resistance and early investigations suggest it has a bio-compatibility similar to titanium, making it a likely future protective coating for the bearing surfaces of artificial hip and knee joints.   The coating was first used in the 1970's for the wear protection of cemented carbide metal cutting tools, where it is still widely exploited, usually as a major constituent of a multi-layered, multi-phased coating.  One variant comprises overlapping layers of TiC, Ti(C,N) and TiN.   Such complex coatings are most easily applied by CVD.

Hungary flag Titán-nitrit bevonat

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The property of some substances to exert a highly harmful (poisonous) influence on man.   This property should be taken into account in connection with cadmium plated vessels.

Hungary flag Mérgezőképesség

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 The ability of a substance to transmit light, incident normally to the surface, without changing its direction.  Some materials, e.g. aluminium vacuum coated glass, of sub-micron thickness, are capable of transmitting light.

Hungary flag Fényáteresztőképesség

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A general term encompassing the frictional, lubrication or wear properties of a material.

Hungary flag Tribológiai jellemzők

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The science and technology of friction, lubrication and wear.  A term first coined in 1966 by a British Government committee.    From the Greek "tribos" (tribos) which means rubbing.

Hungary flag Tribológia

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A method of salt bath nitriding developed by the German company, Degussa, the novel feature of which is the deployment of a titanium crucible that obviates oxidation of the charge caused by solution of previously used steel crucibles and a subsequent decomposition of the sodium cyanide/cyante salts.  Better control of the sodium cyanate content is also achieved by injecting air into the bath;  this promotes the conversion of sodium cyanide to sodium cyanate.  In Germany the process is termed "Teniferbehandlung".

Hungary flag Tufftride folyamat

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Also termed barrelling or rattling.  A technique of deburring or descaling small components of regular shape by placing them in a rotating drum containing fine abrasive powder.  Tumbling can be performed dry or wet.   This technique is sometimes applied as a surface finishing operation and can be used to achieve honed edges of precise radii.  For example, cemented carbide cutting tools are edge radiused in this way, prior to coating with ceramic layers (via CVD).

Hungary flag Koptatás

U

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A process of removing organic compounds, such as grease or oil, from the surface(s) of an object by means of ultrasonic agitation in an organic solvent.   Ultrasonic degreasing can be used in conjunction with immersion solvent cleaning or vapour degreasing which enhances the degreasing effect, especially in the case of intricate objects.

Hungary flag Ultrahangos zsírtalanítás

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The unbalanced magnetron is a magnetron sputter cathode in which the outer magnetic field is made slightly stronger than the inner field, i.e., the magnetic fields are unbalanced.     This enables more ions to escape the cathode and so contribute to raising the current density at the negatively biased substrate; this increases substrate temperatures, obvating the need for auxiliary heaters and improves coating adherence.  The technique was devised by Dr Brian Window of CSIRO, Lindfield Laboratories in Australia during the mid 1980's.  It is the most important devlopments in sputter deposition  technology in recent years.

Hungary flag Kiegyensúlyozatlan magnetron

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Deposition of a tough metallic layer onto the surface of an object prior to cladding by welding;  minimizes the risk of subsequent cracking and spalling of the clad layer

Hungary flag Aláfektetés

V

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Also called evaporation coating.    A method of applying thin metallic or ceramic coatings to substrates at low temperature.   The process is usually carried out under high vacuum conditions (≈10-5 to 10-6 torr).  The coating material can be vapourised using a variety of heat sources; the most common are resistance heaters for low melting point materials, like aluminium, zinc sulphide and antimony, and electron beam heaters for high melting point materials like nickel, molybdenum and aluminium oxide.   The process is highly directional (diagram) and the quality of coating adherence is poor compared to those produced by ion plating.   Hence, such coatings have limited tribological application.   Some coatings like aluminium oxide and zirconium nitride can be produced reactively by evaporating the metal constituent in a partial pressure of oxygen and nitrogen respectively.   For recative deposition the chamber pressure maybe as high as 10-2 torr.   Designs also exist that enable two or more metals to be evaporated simultaneously, enabling the synthesis of alloy coatings.    Aluminium coatings are widely used for decorative purposes on many substrates, including plastics.    They are also widely used in the auto industry for mirrors and lamp reflectors.    In the electronics industry capacitors are fabricated using coatings of the oxides of cerium, silicon, tantalum, titanium and aluminium, while resistors comprising composite coatings of chromium plus silicon dioxide are frequently used.  The latter undergo a post-deposition heat treatment at ≈430°C to develop the required resistance.   The majority of vacuum coatings are less than 1 µm thick.    

Hungary flag Vákuum bevonatolás

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Also called low pressure pasma spraying (LPPS).  A plasma spraying process performed in a chamber that is firstly evacuated to ≈10-2 Torr and secondly progressively back filled with an inert gas to ≈100 Torr.   The plasma torch is often "warmed-up" before the latter working pressure is reached.  VPS has gained popularity because the resulting coatings are denser (>90% of theoretical) than those achieved during conventional plasma spraying, conducted at atmospheric pressure.  The latter method is sometimes called "APS";  air plasma spraying.

Hungary flag Vákuum plazma fémbevonatolás

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Degreasing of a surface achieved by exposure to the action of vapourised organic solvents.  Maybe combined with spraying or immersion in hot liquid solvent in conjunction with ultrasonic agitation.

Hungary flag Gőzöléses zsírtalanítás

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 See vacuum coarting, plasma assisted PVD, PVD and CVD

Hungary flag Gőzöléses bevonatolás

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A surface finishing operation in which the objects under treatment are embedded in a vibrating container containing an abrasive medium.    Also see tumbling.

Hungary flag Vibrációs megmunkálás

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Also called diamond pyramid hardness (DPN).  A square based pyramid indenter, made of diamond,  whose apex has an included angle of 136° is used to indent the surface of a metal or ceramic under the application of a known load.  Following indentation, the average indentation diagonal (d) is measured and Vickers Hardness Number (VHN) is obtained from tables or can be calculated.   VHN is the ratio of the load (P) to surface (projected) area of the indentation, and is usually expressed in kg/mm2.    VHN can be calculated using the formula:

VHN = load/contact area = 1.854 P/d2 = kg/mm2

Nowadays, it is becoming popular to express Vickers hardness in G.Pa; this is achieved by expressing P in Newtons rather than  kilogrammes  (1 kg = 9.80665 N).

VHN is widely used in the heat treatment and surface engineeering sectors and both macro and microindentation versions exist.  Vickers microhardness is especially useful for obtaining hardness-depth profiles of surface engineered materials like nitrided and carburised steels.

Hungary flag Vickers keménység

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A strongly adherent glassy substance applied to (mainly) steels and grey cast-irons as an inexpensive abrasion and corrosion resistant coating.    Vitreous enamel is prepared by smelting together an intimate mixture of refractory materials.   For example, silica, titania, feldspar and china clay together with an appropriate fluxing agent such as borax, sodium silicoborate and nitrates or carbonates of lithium, sodium and potassium.  Melting together of these materials produces a substance resembling glass in texture, but often containing gas bubbles.   The material is then rapidly solidified, e.g., by pouring into water, crushed and ball milled into a fine powder called "frit".  Cast-iron surfaces are prepared by grit blasting, while steels are pickled in acid and given a nickel dip coating.   Frit can be applied to cast-iron surfaces by sieving it onto the surface and heating the objects in a furnace to 900°C; this is called the "dry process".   A more common approach is to apply the frit as a slurry by spraying or dipping; after drying, the frit is fused by heating to ≈750-850°C.    Items are then allowed to cool slowly.   Formerly in wide-use for cook-ware and other house-hold implements;  enamelling is nowadays largely superseded by PTFE coatings.   

Hungary flag Porcelán bevonat

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See vacuum plasma spraying

Hungary flag VPS

W

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The process of removing surface residues by means of clean water or water containing passivating, wetting or detergent additives.    It may be carried out in running or stagnant water, either hot or cold, by immersion or spraying.

Hungary flag Mosás

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Wavelength dispersive x-ray analysis.  Sometimes available as an "add-on" to a standard SEM.  Formerly known as "electron microprobe analysis" (EPMA).  An electron beam (≈20-30 KeV) is focused onto a conducting surface and among the many surface effects, X-rays, of characteristic wavelength are produced.  The optimal sample-electron beam distance is obtained with the aid of a light-optical microscope; this ensures that the X-rays  are brought to focus at the X-ray counter where they are collimated and diffracted by a crystal spectrometer.   The geometry of the crystal is configured to enable diffraction according to the Bragg equation:

nl = 2 d sinq

where is the X-ray wavelength, d is the inerpanar spacing (of the crystal) and q is the angle of diffraction (Bragg angle).   Accordingly, within a given wavelength range, the crystal is "tuned" to the incoming X-rays by varyingq; this is achieved by rotating the crystal.    Several crystals are needed to cover the range of 6.76 nm for B Ka to 0.013 nm for U Ka1.   In this way, most elements can be detected.   The intensity of the diffracted X-rays is proportional to the amount of a given element in the sample, which can be quantified after applying a "ZAF" correction; i.e., after accounting for the effects of atomic number (Z), X-ray absorbtion (A) and X-ray fluorescence (F).  For quantification it is essential to determine the peak count rate and background count rate for an external primary standard, ideally for the pure element.   Elemental mapping, in conjunction with secondary electron imaging is also a useful feature of this method.    For a recent review see:  M. G. Hall, Surf. Eng., 1993, 9, 205-212.

Hungary flag WDX

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The loss of material from a surface when brought into rubbing contact with two or more other surfaces; usually measured as weight loss, volume loss or dimensional change.    The type and amount of wear is determined by many factors.   The most important are atmosphere, contact stresses, contact speed, direction of contact and presence of third-body particles.   The nature of the wear interface is of crucial importance.  Also see seizure  and lubrication.

Hungary flag Kopás

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Service life in terms of material loss through wear; sometimes expressed as the time required to achieve a critical dimensional change or weight loss.

Hungary flag Kopási élettartam

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A general term denoting the response of any given material to wear.   This should be qualified by specifying the wear environment and the rate controlling wear mechanisms.

Hungary flag  Kopási tulajdonságok

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The ability of a material to endure wear

Hungary flag Kopásállóság

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A technique for laying down very thick (≈1 to 10 mm) layers of wear resistant material.   Various  welding techniques can be used, these include metal-inert gas (MIG), tungsten-inert gas (TIG), plasma transferred arc (PTA), submerged arc and manual metal arc.   The latter, because of its relative simplicity,  is found in widest use.   A very broad range of coating materials can be applied.  They include stellites (Co alloys), martensitic and high speed steels, nickel alloys and WC-Co cemented carbides.   After deposition, it is frequently necessary to finish machine the object to size by metal cutting or grinding.   Also see fusion hard facing alloys.

Hungary flag Felrakóhegesztés

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The extent to which a solid surface is wetted by a liquid; usually expressed as wetting angle.  A zero degree wetting angle corresponds to complete wetting, while a high angle of 70 or 80° corresponds to poor wetting.

Hungary flag Nedvesíthetőség vagy nedvesítés

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The ability of a surface engineered material to endure in-service wear, corrosion or fatigue.   The same meaning as durability.

Hungary flag Működési jellemzők

X

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A general purpose method of phase analysis and lattice parameter determination.  The basis of X-ray diffraction is the Bragg equation:

nl = 2dsinq

where  is the wavelength of the X-ray radiation, n is the order of reflectcion, q is the Bragg angle and d is the inter-planar distance of the planes causing diffraction.   By irradiating a sample surface with monochromatic X-rays  (e.g., Cu Ka1) and measuring q,  d is readily determined.  The intensity  of the diffracted X-rays  are also recorded.    Nowadays, d-spacing and X-ray intensity data is obtained using an X-ray goniometer which uses a proportional counter to measure diffraction intensity; an output of intensity versus 2q is obtained.   For a randomly oriented polycrystalline solid, several diffraction peaks of characteristic intensity will be produced.  The international JCPDS data base should be consulted when undertaking phase analysis; this is a major collection of diffraction data.   Much greater detail on X-ray diffraction principles and methods are available in standard texts, e.g., see B. D. Cullity: "Elements of X-ray Diffraction", 2nd ed; 1978, Addison-Wesley, Reading MA.   Also see glancing angle X-ray diffraction.

Hungary flag Röntgensugár elhajlás

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X-ray photoelectron spectroscopy.   The surface under interrogation is irradiated by monochromatic low energy ("soft") x-rays, e.g., Al Ka,  under ultra high vacuum conditions.   This produces an effect termed photoionisation which leads to the emission of photoelelctrons from the atomic cores of the surface atoms.     The latter have a kinetic energy (Ek) that is realted to the incident x-ray energy (hn) and the core binding energy of the elelctron (Eb) by the Einstein relation:

Ek  =  hn - Eb

In XPS, a kinetic energy distribution is obtained, such that a plot of intensity versus binding energy can be derived.  Binding energies corresponding to, for example, 3d, 3p and 3s transitions are obtained.  Their energies are unique to a given element, enabling precise elemental identification.  It is also possible to use this information to gain chemical bonding information, e.g., to demonstrate whether a given element is bonded to another, or not.   XPS can be used on non-conducting surfaces but cannot be generally applied to sample surface areas of less than 1 cm2.   However, at the time of writing, attempts are being made to improve the capability of XPS to enable selected area analysis.

Hungary flag XPS

Y

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See:  Nd-YAG laser.

Hungary flag YAG lézer

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See Nd-YAG laser.

Hungary flag  Yttrium-alumínium lézer

Z

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Also called electrogalvanizing.    An electroplating process in which zinc is deposited on the surface of an object from cyanide,  alkaline non-cyanide,  or acidic chloride baths.   Pure zinc anodes are used.    Zinc plating is applied mainly to steels for corrosion protection and decoration purposes, but the technique has poor levelling capability.    Zinc plated coatings are pure, very ductile and up to 12 µm thick, compared with 80-125 µm for hot dip galvanised layers.

Hungary flag cink horganyzás

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Also called an oxygen probe.   Used for detecting small levels of oxygen in gas carburising furnaces and thereby obtaining an estimate of carbon potential.   From the following reaction:

CO  à C(Fe) + 1/2 O2 

carbon potential can be seen to be proportional to (pCO)/p(O2)1/2.   The zirconium sensor generates an  e.m.f. when brought into contact with oxygen, using air as a reference.   One design of sensor has the following relationship:

e.m.f = 4.9593 x 10-5 T log10 (pO2/0.209)

where T is the absolute temperature of the sample point and pO2 is  the partial pressure of oxygen.    Hence, the measured e.m.f may be directly related to carbon potential.   Also see gaseous carburising. This method has also received rigorous investigation for controlling gaseous nitriding atmospheres; see:  S. Bőhmer et al, Surf. Eng., 1994, 10 (2) 129-135.

Hungary flag Cirkónium-oxigén érzékelő


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