| 摘要 |
PROBLEM TO BE SOLVED: To enable the formation of hard alumite film at high temp. side in comparison with the conventional method and to attain the reduction of electric power cost and the simplification of an equipment by dipping an aluminum material to be treated having smaller treating area than the electrolytic area of a cathodic material into electrolytic solution and executing an anodic- oxidizing treatment. SOLUTION: Into the electrolytic solution 3 for anodic-oxidizing treatment of sulfuric acid, etc., incorporated in an electrolytic vessel 4 providing the cathodic material 2, e.g. the tubular aluminum material 1 having an opening hole 1a is dipped. At this time, the treating area of the aluminum material 1 is set to the small area, such as about 50-90% of the electrolytic surface of the cathodic material 2. Successively, the temp. of the electrolytic solution 3 is set to about 14-22 deg.C and the anodic-oxidizing treatment is executed at about 1.0-1.4 A/dm<2> current density. By this method, the exothermic quantity on the surface of the aluminum material 1 at the time of anodic-oxidizing is small and local temp. rising is restrained and the hard alumite film having the uniform high hardness in each part and about 12-20μm film thickness, is formed without needing the cooling to about 0-10 deg.C with a freezer, etc.
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