Chemistry: electrical and wave energy – Processes and products
Patent
1983-01-04
1986-05-27
Niebling, John F.
Chemistry: electrical and wave energy
Processes and products
148 621, 204 381, 204 40, C25D 1138, C23C 2224
Patent
active
045914168
ABSTRACT:
The present invention includes an aqueous acidic chromate solution, suitable for forming colored chromate coatings on zinc-nickel alloy electrodeposits containing up to about 15% by weight nickel, which solutions have a pH within the range of about 1.3 to about 2.7, a hexavalent chromium concentration of at least 0.5 grams per liter, and preferably about 0.5 to about 100 grams per liter, and which contain sulfate in a weight ratio of SO.sub.4 :Cr.sup.+6 of about 0.025-1.5:1.
The zinc-nickel alloy electrodeposits are preferably immersed in the chromating solution for a period sufficient to form the desired colored chromate coating. In some instances, a flash electrodeposit of zinc may be applied to the zinc-nickel alloy electrodeposit before it is immersed in the chromating solution. Alternatively, the zinc-nickel alloy electrodeposit may be immersed in the chromating solution and the solution electrolyzed, with the zinc-nickel alloy surface as the anode, at low current densities for a short period of time, after which, the electrolysis is discontinued and the zinc-nickel alloy surface is maintained in the chromating solution until the desired colored chromate film is formed.
REFERENCES:
patent: 3855010 (1974-12-01), Sharmaitis et al.
patent: 3895969 (1975-07-01), Miller
patent: 4216272 (1980-08-01), Clauss
patent: 4266988 (1981-05-01), Krippes
patent: 4388160 (1983-06-01), Rynne
H. Silman et al., Protective and Decorative Coatings for Metals, Finishing Publications Ltd., Teddington, Middlesex, England, 1978, pp. 433-435.
A. K. Graham, Electroplating Engineering Handbook, 2nd edition, Reinhold Publishing Corp., New York, 1962, pp. 419-420.
Kamitani Masaaki
Tsuji Hidenori
Ebara-Udylite Co., Ltd.
Leader William T.
Mueller Richard P.
Niebling John F.
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