Treatment of Metal Coatings

1,198,329. Modifying metallic surfaces; electrolytically coating metallic surfaces. ASSOCIATED CHEMICAL COMPANIES Ltd. Aug. 1, 1968. [Aug. 7, 1967], No. 36096/67. Headings C7B and C7U. [Also in Division B2] A metal, e.g. steel or other ferrous metal, zinc or aluminium, the surface of which has been phosphated or electrolytically coated with chromium or chromate or a chromium oxide is contacted with an aqueous solution of a chromic salt of an organic nitrogen base and then heat cured. Examples of the organic base are methyldimethyltrimethyl - t-butyl- or t-octylamine, ethanolamine or cyclohexyl-amine, quaternary ammonium bases containing a substituent, amine oxides containing a substituent, polyalkylene polyamines, heterocyclic bases, guanidine bases or ethylene oxide condensates of certain bases referred to above. The salt may be formed in situ. A wetting agent, e.g. non-ionic, and an organic solvent e.g. tbutanol, isopropanol, and acetone may also be added to the solution. The solution may be used as an electrolyte with the metal as a cathode during treatment. The solution may contain a catalyst, to assist curing, which may be a reducing agent, and may be a salt of ammonia or the organic nitrogen base with sulphuric or sulphamic acids. The surface may be cured at 50 to 250‹ C.