LIQUID TRIVALENT CHROMATE FOR ALUMINUM OR ALUMINUM ALLOY AND METHOD FOR FORMING CORROSION-RESISTANT FILM OVER SURFACE OF ALUMINUM OR ALUMINUM ALLOY BY USING SAME

摘要

Disclosed is a method for forming a film having excellent corrosion resistance and excellent adhesion to coating compositions over the surface of aluminum or an aluminum alloy using a liquid trivalent chromate which contains no harmful hexavalent chromium. Also disclosed is a hexavalent chromium-free liquid trivalent chromate for aluminum or aluminum alloys wherein the concentration of trivalent chromium is within the range of 0.01-100 g/L, the concentration of metal selected from the group consisting of zinc, cobalt, nickel and combinations thereof is within the range of 0.01-100 g/L and the concentration of fluorine is within the range of 0.01-50 g/L.