ZN-NI COMPOSITE ELECTROPLATED STEEL SHEET EXCELLENT IN PROPERTY AFTER COATING

摘要

PURPOSE:To obtain a Zn-Ni composite electroplated steel sheet excellent in properties after coating and adhesive strength of plating by incorporating specific amounts of Mg and cation polymer to a Zn-Ni alloy plating. CONSTITUTION:Mg and cation polymer are incorporated to a Zn-Ni alloy plating by 0.1-10wt.% and 0.001-5wt.%, respectively. As the above cation polymer, quaternary amine polymer is preferred. The above-mentioned combinedly added Mg modifies a phosphate film applied to the plated surface and improves properties after coating, and also, it makes Zn corrosion products dense and stabilizes them and inhibits the progress of corrosion under the coated film. Further, the cation polymer has a function of accelerating the eutectoid of Mg whose deposition potential differs greatly from those of Zn and Ni. By this method, the Zn-Ni composite electroplated steel sheet excellent in properties after coating and adhesive strength of plating can be obtained.