| 摘要 |
PURPOSE:To form an excellent rust preventive film having no surface defect by defatting and washing the surface of aluminum alloy parts then subjecting the parts to electroless nickel plating and further to a chromate treatment. CONSTITUTION:The surface of aluminum alloy parts is defatted and washed and thereafter said parts are subjected to electroless nickel plating, then to a chromate treatment. A nickel plating layer 3 is then selectively formed on the deposited particles 2 of the intermetallic compd., etc. of the alloy exposed on the surface of the aluminum base 1 of the parts and at the same time, the non- plated parts are generated. A chromate layer 4 is selectively formed in the non-plated parts by the succeeding chromate treatment, by which the protective film having excellent corrosion resistance is formed over the entire surface of the aluminum alloy parts. Said layer 3 and layer 4 are respectively as thin as about <=5mum and about <=1mum to give no adverse influence to the dimensional accuracy. Since the above-mentioned surface treatment is accomplished by dipping the parts in the treating liquid, the treatment of the parts having intricate surface shapes is also possible. |
