Process for anodizing aluminum materials and application members thereof

摘要

According to the present invention, an aluminum alloy containing silicon is anodized using an electrolyte including a compound containing an anion having complexing capability such as sodium hydrogenphosphate or tribasic sodium phosphate, a salt of an organic acid containing an oxyacid anion such as sodium citrate or sodium tartrate or an alcohol such as sorbitol, and a halide such as potassium fluoride or sodium fluoride. The use of such an electrolyte results in a reduced amount of silicon being incorporated in the anodic oxide film. When the resulting oxide film is subjected to an electrodeposition treatment such as electroplating or electrolytic coloring, wasteful consumption of electrodeposition current can be inhibited. An aluminum alloy decorative cover is produced by buffing the surface of an aluminum alloy containing silicon, forming the anodized film on the buffed surface, and subjecting the anodized film to sequential nickel and chromium plating. The anodizing process of the invention for anodizing an aluminum alloy containing silicon is used to anodize a spiral scroll member of a compressor and the inner circumferential surface of the cylinder of a cylinder block.