| 摘要 |
409,679. Electrolytic surface treatment of aluminium and its alloys. ALUMINUM COLORS, Inc., 537, East Washington Street, Indianapolis, Indiana, U.S.A.-(Assignees of Work, H. K. ; Oakmont, Pennsylvania, U.S.A.) Aug. 31, 1932, No. 24333. Convention date, Jan. 26. [Class 41.] Oxide coatings are produced by subjecting the metals to anodic treatment in a bath containing sulphuric acid and an organic acid or to a two-stage treatment with separate electrolytes of sulphuric acid and organic acid. Direct or alternating current may be employed Di-basic organic acids such as oxalic, malic, malonic, maleic and succinic acids are preferably employed. In an example the metal is first treated in a bath containing 2-70 per cent of sulphuric acid, with a voltage 35-40, at a temperature below 40‹ C. It is then treated in a bath containing 2-9 per cent of oxalic acid, with a voltage 30-80, at a temperature below 45‹ C. A bath for single-stage treatment may contain 0.5-15 per cent of sulphuric acid and from 0.5 per cent up to the saturation limit of oxalic acid. The acids may be replaced by their ammonium or alkali metal salts in acid solution. |
