METHOD FOR FORMING PROTECTIVE FILM OF METAL, AND PROTECTIVE FILM OF METAL

摘要

PROBLEM TO BE SOLVED: To form a protective film combining uniform, satisfactory appearance and stable corrosion resistance equal to that by treatment with hexavalent chromium on the surfaces of Zn, Ni, Cu, Ag, Fe, Cd, Al, Mg, and their alloys without using harmful hexavalent chromium, nor using fluorine compounds having a strong corrosiveness as essential components.;SOLUTION: The method for forming a protective film of a metal has a process where the surface of a metal is coated with a layer chemically converted from an aqueous acid liquid solution, and a process where the aqueous acid liquid composition is dried without rinsing. The aqueous acidic liquid composition contains (A) at least one kind selected from the group consisting of Ti, V, Mn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, and W, and (B) at least one kind selected from the group consisting of organic acid and/or inorganic acid such as the oxyacid of phosphorus, nitric acid, sulfuric acid, hydrochloric acid, and boric acid and/or their salts, and (C) fluorine as an optional component.;COPYRIGHT: (C)2003,JPO