| 摘要 |
1376120 Chromating Al surfaces PYRENE CHEMICAL SERVICES Ltd 29 Aug 1973 [31 Aug 1972] 40699/73 Heading C7U Al or Al alloy surfaces are sprayed with an acid aqueous solution (pH below 3.5) containing (g./l.) 1.5 to 40 CrO 3 , 0 to 40 P 2 O 5 , 0 to 10g/1F, and 0 to 40 BF4, but containing at least 0.05g./l.F or BF 4 , and which has a total concentration of CrO 3 + P 2 O 5 + F + BF4 of not more than 60g./l. The spraying is arranged to form a film of 10 to 200 ml. of the solution/sq. m. of surface, and the film is rinsed with water after 1 to 20 seconds. The solution may also contain cations of alkali metals, Cr, Zn, Ba or Al, and ammonium ions, and accelerators e.g. complex cyanides, tungstic acid, molybdic acid, vanadic acid or their water soluble salts, or glycerine. The surface may be subsequently rinsed with a solution containing hexavalent chromium. |
