Abstract: For producing corrosion resistant yellow passivate layers on zinc and zinc alloy surfaces, an aqueous reaction solution is utilized that contains trivalent chromium ions, at least one acid as well as at least one heteroaromatic compound selected from the group comprising nicotinic acid, the salts and derivatives thereof.

Abstract: For producing corrosion resistant yellow passivate layers on zinc and zinc alloy surfaces, an aqueous reaction solution is utilized that contains trivalent chromium ions, at least one acid as well as at least one heteroaromatic compound selected from the group comprising nicotinic acid, the salts and derivatives thereof.

Abstract: The invention relates to a method for producing a coating layer protecting against corrosion wherein a surface which is to be treated is brought into contact with an aqueous treatment solution containing chromium(III) ions and at least one phosphate compound, wherein the ratio of the molar concentration of the chromium(III) ions to the molar concentration of the at least one phosphate compound (calculated as orthophosphate) lies between 1:1.5 and 1:3. The method improves the corrosion protection of metallic, in particular, zinc-containing, surfaces provided with conversion layers. The decorative and functional properties of the surface are maintained or improved. Furthermore, the known problems resulting from the use of chromium(VI)-containing compounds or from post-treatments with polymer dispersions are avoided.