A method for the production of uniformly dyed oxide layers of aluminum and aluminum alloys by anodic oxidation

摘要

850,576. Anodising aluminium and alloys thereof. KAISER ALUMINUM & CHEMICAL CORPORATION. April 10, 1959 [April 14,1958 No. 12242/59. Class 41 An abradant resistant anodised surface is imparted to aluminium and its alloys, by using as electrolyte an aqueous solution containing sulpho-salicylic acid and either sulphuric acid or a metal sulphate, e.g. ferric sulphate. In a preferred process, the aluminium surface is (1) treated with alkali solution containing a little sodium fluoride, (2) washed with nitric acid, (3) anodised at room temperature with an electrolyte containing 7 to 15 % sulphosalicylic acid and a little sulphuric acid for up to 2 hours, (4) sealed with hot soapy water. Alloys, especially the one containing copper, are coloured, when H 2 SO 4 reduced to a content of À1 to 1 % of total electrolyte. Either A.C. or D.C. or a combination may be used. U.S.A. Specification 2,719,781 is referred to.