| 摘要 |
1,169,647. Anodizing. MATSUSHITA ELECTRIC INDUSTRIAL CO. Ltd. Aug.24, 1967 [Sept.5, 1966; Sept.30, 1966; Dec.16, 1966], No.39080/67. Heading C7B. A method of forming an anodic oxide film on the surface of aluminium or aluminium alloy comprises forming an anodic oxide film having a smaller thickness than that desired, then forming cracks over the whole region of the film by elongating the film in at least one direction, then again anodically oxidizing to increase the thickness of the film. Preferably the second oxidation does not increase the film thickness more than 10 times the thickness at the time of crack formation. The cracks may be formed by rolling with rollers having smooth or ribbed surfaces, or by temperature change, crack formation resulting from the different expansion co-efficients of the film and its base. The process of film cracking followed by further anodizing may be repeated to form a film having a high density of cracks when the base is bent, the film having improved insulating properties. Sulphuric acid, oxalic acid, phosphoric acid, chromic acid, sulphamic acid, boric acid or ammonium borate may be used in the anodizing electrolyte.
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