GB1362374A - Method of and composition for anti-corrosive protection by reduc tion of ionised metals on metal substrate - Google Patents

Abstract

1362374 Coating with metal L WISNIEWSKI 10 June 1971 [17 June 1970] 19963/71 Headings C7B and C7F A film of metal (e.g containing Zn, Cd, Sn, Pb, Ni or Ti) is provided on an Fe or steel substrate (e.g. a bridge) by reduction of an ionized compound of the metal using elemental metal (such as Mg, Al, Zn, Cd or an alloy thereof, in powder form) as reducing agent. The process comprises applying to the substrate a wet coating composition containing the elemental metal, an ionizable metal compound and an organic liquid; allowing the coating composition to dry; and wetting the dried coating with an acid electrolyte containing the same or a different ionizable metal compound. Thereby, the metal compound(s) is/are reduced to the elemental state to form a metallic film which comprises the metal(s) of the compound(s) and elemental metal surplus to the reduction process. The ionizable compound(s) may be perchlorates, chlorates, chlorides acetates carbonates or oxides. The acid electrolyte, may comprise HClO 4 , CH 3 COOH or HCl thickened by hydroxyethyl cellulose. It may be applied by a brush, roller, spray gun or by dipping. Alternatively, it may be applied by a wire brush or roller of Zn, Cd, Pb or Ni connected as anode relative to the substrate, thereby reinforcing film deposition by simultaneous electrolysis. The coating composition may comprise, as organic liquid, xylene, toluene and alcohols and additionally may contain paraformaldehyde and, as binder, ethyl cellulose. Prior to coating, rust may be removed by a wire brush which may be electrically connected.