Abstract: The invention relates to a process for producing a corrosion-inhibiting coating for substrates having a surface consisting of zinc, magnesium, aluminum or one of their alloys, wherein the surface to be treated is brought into contact in direct succession with two aqueous treatment solutions containing chromium(III) ions, metal ions of the substrate surface to be treated and at least one complexing agent. The first treatment solution has a pH in the range from 1.0 to 4.0, while the second treatment solution has a pH of from 3.0 to 12.0. The process of the invention produces a smaller amount of wastewater polluted with heavy metals.

Abstract: 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.

Abstract: The invention relates to a process for producing a corrosion-inhibiting coating for substrates having a surface consisting of zinc, magnesium, aluminium or one of their alloys, wherein the surface to be treated is brought into contact in direct succession with two aqueous treatment solutions containing chromium(III) ions, metal ions of the substrate surface to be treated and at least one complexing agent. The first treatment solution has a pH in the range from 1.0 to 4.0, while the second treatment solution has a pH of from 3.0 to 12.0. The process of the invention produces a smaller amount of wastewater polluted with heavy metals.

Abstract: 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.