Patent ID: 6503565
Filing Date: 2003-01-07
Classification: C23C,C23G

Abstract:
A process for treating a surface of a metal selected from the group consisting of aluminum, steel, zinc, cadmium, magnesium and their alloys, to remove contaminants and to remove smut from the surface, comprising the steps of:(a) contacting the metal surface having contaminants thereon with an alkaline cleaning solution to remove the contaminants, said alkaline solution causing the formation of smut on the metal surface; and (b) treating the alkaline treated metal surface by contact with a sufficient amount of an acidic, rare earth ion desmutting solution, having a pH of less than 1, for a sufficient time to remove smut formed on said metal surface by the treatment with said alkaline cleaning solution of step (a), without formation of a rare earth metalâ€”containing coating on the cleaned metal surface wherein the smut removal is effected by reaction of the rare earth ions and the acid with the smut on the metal surface.