The white metals are a series of often decorative bright metal

alloy An alloy is a mixture of chemical elements of which in most cases at least one is a metal, metallic element, although it is also sometimes used for mixtures of elements; herein only metallic alloys are described. Metallic alloys often have prop ...

s used as a base for plated silverware, ornaments or novelties, as well as any of several

lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...

-based or

tin Tin is a chemical element; it has symbol Sn () and atomic number 50. A silvery-colored metal, tin is soft enough to be cut with little force, and a bar of tin can be bent by hand with little effort. When bent, a bar of tin makes a sound, the ...

-based alloys used for things like bearings,

jewellery Jewellery (or jewelry in American English) consists of decorative items worn for personal adornment such as brooches, ring (jewellery), rings, necklaces, earrings, pendants, bracelets, and cufflinks. Jewellery may be attached to the body or the ...

, miniature figures, fusible plugs, some

medal A medal or medallion is a small portable artistic object, a thin disc, normally of metal, carrying a design, usually on both sides. They typically have a commemorative purpose of some kind, and many are presented as awards. They may be in ...

s and metal

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * ...

. The term is also used in the antiques trade for an item suspected of being silver, but not hallmarked. A white metal alloy may include

antimony Antimony is a chemical element; it has chemical symbol, symbol Sb () and atomic number 51. A lustrous grey metal or metalloid, it is found in nature mainly as the sulfide mineral stibnite (). Antimony compounds have been known since ancient t ...

cadmium Cadmium is a chemical element; it has chemical symbol, symbol Cd and atomic number 48. This soft, silvery-white metal is chemically similar to the two other stable metals in group 12 element, group 12, zinc and mercury (element), mercury. Like z ...

bismuth Bismuth is a chemical element; it has symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs nat ...

, and

zinc Zinc is a chemical element; it has symbol Zn and atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic tabl ...

(some of which are quite toxic). Not all of these

metal A metal () is a material that, when polished or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, electricity and thermal conductivity, heat relatively well. These properties are all associated wit ...

s are found in all white metal alloys. Metals are mixed to achieve a desired goal or need. As an example, a base metal for jewellery needs to be castable, polishable, have good flow characteristics, have the ability to cast fine detail without an excessive amount of

porosity Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure ...

and cast at between .

Silver

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 hallmarks, but which are nonetheless understood to be silver and are priced accordingly.

Tin-lead and tin-copper alloys

Tin-lead and tin-

copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...

alloys such as Babbitt metal have a low melting point, which is ideal for use as

solder Solder (; North American English, NA: ) is a fusible alloy, fusible metal alloy used to create a permanent bond between metal workpieces. Solder is melted in order to wet the parts of the joint, where it adheres to and connects the pieces aft ...

, but these alloys also have ideal characteristics for

plain bearing file:NYC 100-driving-axle-friction-bearing.jpg, Plain bearing on a 1906 S-Motor locomotive showing the axle, bearing, oil supply and oiling pad file:Linear-table with detail numbered.png, A sliding table with four cylindrical bearings file:GWR Spo ...

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 An intermetallic (also called intermetallic compound, intermetallic alloy, ordered intermetallic alloy, long-range-ordered alloy) is a type of metallic alloy that forms an ordered solid-state compound between two or more metallic elements. Inte ...

compounds are hard and wear-resistant but brittle. By themselves, they 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. That wear also provides channels to allow in

lubricant A lubricant (sometimes shortened to lube) is a substance that helps to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. It may also have the function of transmitting forces, ...

(

oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) and lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturate ...

s). All bearing metals contain

(Sb), which forms hard cubic crystals.

Applications

White metals are commonly used in bearings and bushings because of their high load-bearing capacity and self-lubricating properties, which reduce friction and extend the lifespan of these components. In the

automotive industry The automotive industry comprises a wide range of company, companies and organizations involved in the design, Business development, development, manufacturing, marketing, selling, Maintenance, repairing, and Custom car, modification of motor ve ...

, they are found in engine components like crankshaft and connecting rod bearings. Additionally, white metal is popular in

and decorative items due to its cost-effectiveness and ability to mimic more expensive metals like

silver Silver is a chemical element; it has Symbol (chemistry), symbol Ag () and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. ...

. In the printing industry, white metal alloys were historically used to cast typefaces.

References

{{DEFAULTSORT:White Metal Alloys Bearings (mechanical)

Silver

Tin-lead and tin-copper alloys

Applications

See also

References