Chemistry: electrical and wave energy – Processes and products
Patent
1982-02-22
1983-11-22
Douglas, Winston A.
Chemistry: electrical and wave energy
Processes and products
204 35R, 204 41, C25D 514, C25D 540
Patent
active
044167385
ABSTRACT:
A method of electroplating chromium onto a metal article includes an electrolytic surface treatment step and a plating step. In the electrolytic surface treatment step the article is immersed in an alkaline solution of a cyanide salt and an electrical potential is applied to the article and reversed in polarity at predetermined intervals. The potential is preferably applied in alternating 15 second and 5 second intervals, the polarity of the potential applied to the article being positive during the 15 second intervals and negative during the 5 second intervals. A potential of between about 4 to 6 volts is preferred. The potential is applied to the article for a period of 3 to 15 minutes, preferably beginning and ending with a 15 second interval during which the polarity of the potential is positive. The article is then immersed while still wet in a chromic acid electroplating bath. After several minutes a negative plating potential is gradually applied to the article until a desired current density is obtained. Chromium is continuously plated onto the article until a sufficient thickness of chromium is obtained. The method is particularly useful for plating chromium onto a previously chromium-plated article to form a durable chromium plating.
REFERENCES:
patent: 1774901 (1930-09-01), Piersol
patent: 1942356 (1934-01-01), Fink et al.
patent: 2078868 (1937-04-01), Oplinger
patent: 2678908 (1954-05-01), Tucker
patent: 2856334 (1958-10-01), Topelian
patent: 2915444 (1959-12-01), Meyer
patent: 3388049 (1968-06-01), de Castelet
patent: 3551302 (1970-12-01), Wood et al.
patent: 3770286 (1973-11-01), Angilella et al.
F. A. Lowenheim, Electroplating, McGraw-Hill Book Co., New York, pp. 78-79 (1978).
Metal Finishing Guidebook and Directory 1967, Metals and Plastics Publications, Inc., Westwood, N.J. pp. 188, 190.
Douglas Winston A.
Leader William
The Boeing Company
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