| 摘要 |
395,390. Electrolytic surface treatment of aluminium and its alloys. GOWER, C. H. R. and BOWEN, E. WINDSOR-, 8, Clement's Inn Passage, London. Jan. 6, 1932, No. 429. [Class 41.] The metals are treated anodically in a bath containing an aluminium salt as an initial component. A suitable electrolyte for producing a soft coating is obtained by mixing 160 litres of dilute sulphuric acid containing 2À5 parts of acid to 2 parts of water with 20 litres of a 20 per cent solution of aluminium sulphate. For a hard coating acid of lower strength is employed. The voltage may be 80-100 and the temperature 60-65‹ F. but not greater than 70‹ F. For soft coatings a small quantity, say 1 per cent, of a water-dispersible colloid such as an albuminoid or a carbohydrate or polysaccharide is added. Dextrine, gum traga-, canth, gum acacia, gum ghatti, agar or an aqueous dispersion of Iceland moss are suitable additions. Organic dyes or metallic salts imparting colour to the coatings may be incorporated in the baths or the coated articles may, be subsequently subjected to solutions of these substances. Articles may be continuously conveyed through the baths. |
