Silvering

Silvering 

(Russian, serebrenie), the application of a coating of silver to an object. Such coatings usually range from a fraction of a micron to 30 microns in thickness. Silver coatings are used for decorative purposes and to provide protection against corrosion in aggressive media, to increase electrical conductivity, reflectivity, or antifriction properties, and to decrease contact resistance. A coating of silver may also be used as a base for the deposition of other noble metals.

The most important method of applying silver coatings is electroplating in cyanide plating solutions, which ensure a high quality of coating (seeELECTROPLATING TECHNOLOGY). Non-cyanide electrolytes in the form of other complex silver salts are rarely used. Silver coatings are applied by cladding in the manufacture of bimetallic sheets, pipes, wire, and blanks for contacts. In the case of nonmetallic articles, such as plastic or glass products, the coatings are generally applied by chemical means, the condensation of silver vapor in a vacuum, or cathode sputtering. The chemical method involves the reduction of silver from aqueous solutions of silver salts by reducing agents, such as glucose, tartrates, and formaldehyde. For ceramics and glass, the silver is burned in by reduction from salts at high temperatures.

The thickness chosen for a silver coating depends on the conditions under which the article will be used and on the techniques employed to apply the coating. Food-industry equipment, tableware, and dishes are sometimes coated with silver, as are the working surfaces of mirrors, projectors, and motor vehicle headlights. Silver coatings are also used, for example, in the manufacture of steel-backed ball bearings.

REFERENCES

Iampol’skii, A. M., and V. A. Il’in. Kratkii spravochnik gal’vano-tekhnika. Moscow-Leningrad, 1962.
Fedot’ev, N. P., V. A. Il’in, and I. N. Chernozatonskaia. Elektro-osazhdenie serebra iz rastvorov netsianistykh kompleksnykh solei. Leningrad, 1962.
[Bondarev, V. V.] Novoe v. nanesenii gal’vanopokrytii blagorodnykh melallov. Moscow, 1970.
Lainer, V. I. Zashchitnye pokrytiia melallov. Moscow, 1974.

V. V. BONDAREV