Effect of Surface Modification on Corrosion Resistance of Cu-6Zn Alloy for Building Decoration

Four kinds of passivation films were prepared on the surface of Cu-6Zn alloy by chemical dipping method —— no rare earth salt (No. 1), single Ce salt (No. 2), single La salt (No. 3) and mixed (Ce+La) ) salt (No. 4) passivation films. The thickness of the four passivation films and their corrosion resistance were compared and analyzed, and the film forming mechanism was discussed. The results showed that the order of the thickness of the four passivation films from high to low was: No. 4 > No. 3 > No. 2 > No. 1; and the phases of No. 4 film were mainly CuZn, Cu₂O, CeO₂, La(OH)₃ and Ce(OH)₄. The corrosion resistance of the four passivation film samples and bare steel sample in descending order was: No. 4 > No. 3 > No. 2 > No. 1 > bare sample. The mixed (Ce+La) salt passivation film could play a very good protective effect on the Cu-6Zn alloy and had the best corrosion resistance.