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Glossary of MinSE


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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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