| 摘要 |
PURPOSE:To form chromate film having excellent corrosion resistance, adhesion of painting and corrosion resistance of painting after the heat treatment by treating the surface of Al and an Al alloy with a chromate treating liquid having a specific compsn. and concn. CONSTITUTION:The surface of Al and an Al alloy or a member formed by coating Al or an Al alloy on various kinds of base plates is treated with a chromate treating liquid having the following compsn. in order to improve the corrosion resistance, adhesion of parting and corrosion resistance of painting after the heat treatment: The aq. soln. contg. 1-50g/l chromic anhydride or 2- 100l dichromic acid, about 0.1g/l an F compd. such as HF, 0.05-40g/l a phosphoric acid compd. such as H3PO4 in terms of concn. of phosphate ion and a proper amt. of a hydrochloric acid radical, sulfuric acid radical and nitric acid radical and contg. further 0.1-5g/l a water-soluble org. compd. such as polyvinyl pyrolidone. The Al parts, etc. to be treated are dipped for 5-30sec in the above-mentioned chromate treating liquid to form a chromate film on the surface. |
