New and unique aluminum plating method
AssigneeFord Motor Company
InventorGarrett H. Napier
Life of this patent
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Abstract
A method of plating aluminum parts is disclosed, which provides improved adhesion of the plated system with decreased restraints on transfer time between steps. The aluminum part must contain 1-8% alloyed zinc and be cleaned to be free of grease and organic contaminants, such as by the use of alkaline and etching cleaners. The part is then cathodically cleaned employing sulfuric acid, to be free of any oxide film. While in the latter condition, cyanide and borate salts are cathodically deposited (Ph 7.5-10.5) permitting increased transfer time, up to 1 hour, before metal plating. The salt coated part is immersed in an electrolytic cell to displace the salt coating with a bronze strike containing 58-88% tin. Finally a lustrous decorative coating system is plated thereover.
Claims11
A method of plating at least one designated surface of an aluminum alloy article, comprising:
- (a) selecting said aluminum alloy article to contain 1-8% zinc,
- (b) cleaning said surface to be free of grease and/or organic contaminants,
- (c) cathodically cleaning said surface to be free of any oxide film,
- (d) while in the substantially oxide free condition, subjecting said surface to electrolysis in an electrolytic cell having an electrolyte containing a soluble cyanide and having a pH of 9-10.5 in a manner to leave a cyanide salt coating said surface after removal from said electrolyte,
- (e) within one hour after exposure of said surface to the atmosphere after step (d), immersing said article in an electrolytic cell arranged to displace said salt coating with an electrolytic bronze coating, and
- (f) electrolytically depositing a lustrous decorative coating system thereover.
In a method of electroplating nickel and chromium onto an aluminum based article containing 1-8% zinc, the steps comprising:
- (a) after having substantially removed the aluminum oxide and other contaminants from the surface of said article, immersing the cleansed article as a cathode into an electrolytic cell having an electrolyte containing an aqueous solution of a soluble cyanide,
- (b) controlling the pH of said electrolyte to be in the range of 9.0-10.5 and the temperature within the range of 60.degree.-180.degree. F.,
- (c) applying a current through said electrolyte having a current density of 10-30 ASF per square foot for a period of time of at least 0.75 minutes,
- (d) withdrawing said article from said electrolyte without protection from the atmosphere, and
- (e) within a period of 1 hour or less after exposure to the atmosphere, immersing said article in a bronze plating cell and passing a current therethrough, with the article constituted as a cathode, to deposit a thin bronze coating.
A method of plating aluminum comprising:
- (a) preparing an aluminum based article containing 1-8% zinc and having a surface designated to be plated,
- (b) cleansing said designated surface to be substantially free of contaminants including any oxide film,
- (c) electrolytically while in the oxide free condition, immersing said cleansed article as a cathode into an electrolytic cell having an electrolyte constituted of an aqueous solution with 2-12% sulfuric acid,
- (d) immediately after removal of said article from the electrolyte in step (c), subjecting said surface to electrolysis in an electrolytic cell having an electrolyte containing a soluble cyanide and boric acid and having a pH of 9-10.5 in a manner to leave a coating containing a uniform dispersion of cyanide and borate salts after removal from said electrolyte,
- (e) within a period of 1 hour after exposing said coated article to the atmosphere, immersing said coated article in an electrolytic cell having an electrolyte effective to deposit a bronze strike, said coating separating from said article by dissolution upon coming into contact with said aqueous electrolyte,
- (f) after a period of no less than 1 minute, passing current through the electrolyte in step (e) so as to effect the deposition of a bronze coating in place of said cyanide and borate salt coating, and
- (g) depositing thereover a metallic coating system of desired luster and decoration.
Dependencies are inferred from the claim text.