| 摘要 |
447,420. Electrolytic sur ace treatment of aluminium and its alloys. GOWER, C. H. R., and BOWEN, E. WINDSOR-, Thames Factory, Rainville Road, Hammersmith, London. Nov. 17, 1934, No. 33156. [Class 41] The articles are subjected to anodic treatment in a bath containing acetic acid and a relatively small proportion of phosphoric and sulphuric acids with or without boric acid, the bath being maintained in motion ; the metal is thereby cleaned and provided with a thin and even film of oxide which may then be thickened by further anodic treatment in usual baths. Suitable proportions are 10-15 per cent by volume of acetic acid, 2-2¢ per cent of phosphoric acid and 2¢-3 per cent of sulphuric acid together with ¢-1 oz. per gallon of boric acid. With current density 3-4 amps. per sq. ft. and temperature 80-90‹ F. the treatment is completed in 1-5 minutes. A coating sufficient for protective purposes may be obtained by extended treatment in the same bath or by further anodic treatment in a chromic acid, oxalic acid or other bath. Specifications 395,390, 396,743, 412,193, and 447,421 are referred to, |
