Patent ID: 6432225
Filing Date: 2002-08-13
Classification: C23C

Abstract:
An improved process that is commercially practical for forming an oxide film cobalt conversion coating exhibiting corrosion resistance and paint adhesion properties on a substrate, where said substrate is aluminum or aluminum alloy, said process comprising the steps of:(a) providing an oxide film forming cobalt conversion solution comprising an aqueous reaction solution, containing no triethanolamine (TEA), prepared by reacting the following starting materials: (1) a water soluble cobalt-II salt CoX2 where X=Cl, Br, NO3, CN, SCN, &frac13;PO4, Â½SO4, Â½CO3, formate, or acetate; (2) a water soluble complexing agent selected from the group consisting of MeNO2, MeAc, MeFm, NH4Ac, and NH4Fm, where Me is Na, K, or Li; Ac is acetate; and Fm is formate; (3) an accelerator selected from the group consisting of NaClO3, NaBrO3, and NaIO3; and (4) water; and (b) contacting said substrate with said aqueous reaction solution for a sufficient amount of time to oxidize the surface of said substrate, whereby said oxide film cobalt conversion coating is formed, thereby imparting corrosion resistance and paint adhesion properties to said substrate.