| 摘要 |
1,128,369. Conversion coatings on aluminium. ALLIED RESEARCH PRODUCTS Inc. Dec.22, 1965 [Dec.29, 1964], No.54319/65. Heading C7U. Aluminium and its alloys are coated by treatment with an aqueous solution containing hexanalent chromium, a fluo compound, a soluble tungstate or a phosphate and said phosphate calculated as P 2 O 5 is present in a weight ratio of from 1:10 to 1:150 to said tungstate calculated as WO 3 . The solution may also contain ferricyanic acid, ferrocyanic acid and their soluble salts and the pH is adjusted by the addition of nitric acid to 0.5 to 3.0. The solution may be formed from chromic acid or a soluble salt thereof, hydrofluoric acid, fluoboric acid, fluosilicic acid or their soluble salts, phosphoric acid or a soluble phosphate, arsenic pentoxide or a soluble salt of arsenic acid and sodium or potassium tungstate. The concentration of the ingredients in solution is 0‹5 - 50 g/l CrO 3 , 0À05 - 5 g/l hydrofluoric acid or 0.075 - 8 g/l fluosilicic acid or 3À3 - 33 g/l fluoboric acid, 0.35 - 7 g/l WO 3 . The temperature of the solution is 60‹ - 120‹ F. and the treatment time 5 seconds to 15 minutes. |
