摘要 |
PURPOSE:To form a treated surface layer excellent in quality by treating aluminum alloy casting or die casting with a soln. contg. phosphoric acid and a soln. contg. hydrofluoric acid, sulfuric acid and nitric acid successively and thereafter performing post-treatment such as chemical film treatment. CONSTITUTION:Aluminum alloy casting or die casting is treated with a soln. contg. essentially phosphoric acid and a soln. contg. 2-20wt% (expressed in terms of F<->) hydrofluric acid and/or fluorine compound, 20-40wt% (expressed in terms of SO4<2->) sulfuric acid and 30-70wt% (expressed in terms of NO3<->) nitric acid successively to perform chemical polishing and furthermore, if necessary, mechanical abrasion is performed by vibrational barrel treatment and/or blast treatment. Then, the aluminum alloy subjected to pretreatment is subjected to post-treatment with at least one kind of treatment among chemical film treatment, anodic oxidation treatment, coloring treatment, painting treatment, chemical plating treatment and electrical plating treatment. By these treatment, a product having a surface layer excellent in performance and appearance and high dimensional accuracy is obtained. |