Corrosion protection of zinc, aluminum and/or magnesium surfaces such as motor vehicle bodies, comprises passivation using complex fluorides of Ti, Zr, Hf, Si and/or B and organic polymers

摘要

Corrosion protection of metal surfaces with at least 90 % zinc, aluminum and/or magnesium, comprises cleaning, passivation and painting. The passivation is carried out using an aqueous solution having a pH of 1-12 and containing 20-50 mg/l complex fluorides of Ti, Zr, Hf, Si and/or B and 50-200 mg/l organic polymers without formation of a crystalline zinc containing phosphate layer. A process for the corrosion protection of motor vehicle bodies or household articles, having at least one metal surface that comprises at least 90% of zinc, aluminum and/or magnesium and/or corresponding alloys of these metals or with other alloying components, comprises cleaning, passivation and painting. The passivation is carried out using an aqueous solution (I) having a pH of 1-12 and containing 20-50 mg/l complex fluorides of Ti, Zr, Hf, Si and/or B (w.r.t. Ti, Zr, Hf, Si and/or B content) and 50-200 mg/l organic polymers. The composition of the aqueous solution (I) is such that no crystalline zinc containing phosphate layer is formed.