- White metal
The white metals are any of several light-colored
alloy s used as a base for platedsilverware , ornaments or novelties, as well as any of severallead -base ortin -base alloys used for things like bearings,jewellery ,miniature figure s,fusible plug s, somemedal s and metal type.Some of the
metal s that make up a white metal alloy areantimony ,tin ,lead ,cadmium ,bismuth , andzinc . Not all of these metals are found in all white metal alloys but are mixed to achieve a desired goal or need. As an example, a base metal for jewelry needs to be castable, polishable, have good flow characteristics, have the ability to cast fine detail without an excessive amount ofporosity and cast at between 230 °C and 300 °C (450 °F and 575 °F).It should be noted that in compliance with British law, the British fine art trade uses the term "white metal" in auction catalogues to describe foreign silver items which do not carry British Assay Office marks, but which are nonetheless understood to be silver and are priced accordingly.
Tin-lead and tin-copper alloys
Tin-lead & tin-
copper alloys have a low melting point that is ideal for use assolder , but these alloys also have ideal characteristics forplain bearing s. Most importantly for bearings, the material should be hard and wear resistant and have a low coefficient of friction. It must also be shock resistant, tough and sufficiently ductile to allow for slight misalignment prior to running in.Pure metals are soft, tough and ductile with a high coefficient of friction. Intermetallic compounds are hard and wear resistant but brittle. By themselves, these do not make ideal bearing materials.
Alloys consist of small particles of a hard compound embedded in the tough, ductile background of a solid solution. In service the latter can wear away slightly leaving the hard compound to carry the load. This wear also provides channels to allow in
lubricant (oil s). All bearing metals containantimony (Sb) which forms hard cubic crystals.ee also
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Babbitt metal
*Britannia metal
*Pewter
*Pot metal
*Punchcutting
*ZAMAK External links
* [http://www.nomastedio.com/Tienda/toy_soldiers_shop.html Miniatures en métal, soldats & miniatures de plomb, objets de collections]
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