Abstract: The present invention generally relates to an aqueous solution for the formation of a passivation layer on a zinc layer or zinc-alloy layer. More particularly, the invention relates to the formation of a black passivation layer on a zinc layer or zinc-alloy layer, which passivation layer is substantially free of hexavalent chromium. Furthermore, the present invention relates to method for the formation of a passivation layer on a zinc layer or zinc-alloy layer, as well as a passivation layer on a zinc layer or zinc-alloy layer itself. The solution used contains trivalent chromium ions, nitrate ions, an organic acid and a dithioglycolate.

Abstract: A method for coating a metal having a metal surface layer having an oxide layer thereon with a corrosion-inhibiting polymer resin layer. The method comprises contacting the surface of the metal with a pretreatment composition comprising an organophosphorus compound comprising phosphorus and an alkyl group capable of interacting with a plastic monomer resin or plastic polymer resin; and contacting the pretreated metal surface with a sealant composition comprising the plastic monomeric and/or polymeric resin.

Abstract: A method for coating a metal having a metal surface layer having an oxide layer thereon with a corrosion-inhibiting polymer resin layer. The method comprises contacting the surface of the metal with a pretreatment composition comprising an organophosphorus compound comprising phosphorus having an oxidation state of +3 and an alkyl group capable of interacting with a plastic monomer resin or plastic polymer resin; and contacting the pretreated metal surface with a sealant composition comprising the plastic monomeric and/or polymeric resin.