Anti-corrosive treatment for surfaces made of zinc and zinc alloys

摘要

The invention refers to a process for producing an anticorrosive coating in which a surface to be treated is brought into contact with an aqueous treatment solution containing chromium(III) ions and at least one phosphate compound and an organosol. The corrosive protection of metal surfaces, in particular those containing zinc and zinciferous surfaces with conversion layers is improved. The decorative and functional properties of the surfaces are retained or improved. In addition, the well-known problems associated with the use of compounds containing chromium(VI) or with multi-stage processes are avoided in which a passivation layer containing chromium ions and a sealing are applied one after the other.

主权项

1. Process for creating a corrosion protection coating layer, comprising:
providing one or more alkoxysilanes according to formula (1)
R4-xSi(OR1)x  (1)with the residues R, identical or different from one another, representing a substituted or non-substituted hydrocarbon group with between 1 and 22 hydrocarbon atoms and x is equal to 1, 2 or 3 and R1 stands for a substituted or non-substituted hydrocarbon group with between 1 and 8 hydrocarbon atoms;
providing an aqueous acid solution; hydrolyzing the one or more alkoxysilanes according to formula (1) with the aqueous acid solution to form a hydrolysate; providing one or more alkoxides according to formula (2)
Me(OR2)n  (2) wherein Me stands for Ti, Zr, Hf, Al, Si and n stands for the oxidation level of Me and R2 is selected from substituted or unsubstituted hydrocarbon groups containing between 1 and 8 carbon atoms; combining the hydrolysate with the one or more alkoxides according to formula (2) to form an organosol; combining the organosol with chromium(III) ions and at least one phosphate compound to form an aqueous treatment solution; and contacting a surface to be treated with the aqueous treatment solution to form a corrosion protection layer on the surface; wherein the aqueous treatment solution is free of inorganic or organic peroxides.