Thursday, February 21, 2008

Nickel Plating

Nickel is one of the most important metals applied by electrodeposition. The plate is used principally as a bright coating underneath a much thinner chromium electroplate to provide a highly lustrous and corrosion-protective finish for articles of steel, brass, zinc die castings, chemically metalized plastics, and, to a much smaller extent, for coatings on aluminum and magnesium alloys. The protection of the underlying metal depends primarily on the nickel plate, with the thin chromium overlay conferring a permanently nontarnishing, hard, wear-resistant surface. To a far lesser extent, and only for mild exposures, thin gold or brass electroplate with a clear lacquer finish is used as a decorative coating on thin bright nickel deposits. Nickel coating alone are also used industrially to afford corrosion protection to prevent contamination of a product. Because of favorable mechanical properties, nickel electrodeposits are used for electroforming of printing plates, phonographs record stumpers’, foil, tubes, screens, and many other articles.

The history of the electrodepositing of nickel goes back more than 125 years. It began in 1843 that describe the first apparently sound nickel plate, which obtained from a bath containing nickel and ammonium sulfates. The first do nickel plating on a truly commercial basis used double salt baths, including both sulfate and chloride, and was probably the first to recognize the importance of impurities in the plating bath. He employed cast soluble anode which contained silicon, iron, and carbon. The only early developments that have survived, however, are Weston’s introduction of boric acid into the bath, the use of chlorides and promote anode corrosion, and the discovery about 1912, that cadmium salt act as brighteners. Electrolytic nickel refining profited by the experience of the nickel platter and has made use of warm nickel sulfate-boric acid solution since 1894.
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