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Glossary of MinSE


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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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