| 摘要 |
PURPOSE:To improve the treatability of an Al casting and to facilitate painting by subjecting successively said casting to a treatment with a soln. consisting essentially of phosphoric acid, oscillating barrel treatment, and chemical film treatment then to painting. CONSTITUTION:An Al alloy casting or Al alloy die casting is treated by a soln. consisting essentially of phosphoric acid and is thus chemically polished. The casting is then subjected to an oscillating barrel treatment and/or blasting treatment to prepare the surface thereof. The casting is further subjected to general degreasing treatment and chemical film formation (or anodizing and sealing), whereby a uniform film is formed thereon. The casting is finally subjected to painting by a conventional method followed by drying or baking. The casting may be chemically polished by a soln. contg. at least one kind of hydrofluoric acid and fluorine compd. and phosphoric acid and nitric acid according to need after it is chemically polished with the soln. consisting essentially of phosphoric acid. |
