| abstract |
A zinciferous coated steel sheet comprises a steel sheet, a zinciferous coating layer formed on the steel sheet, a Fe-Ni-Zn-O film formed on the zinciferous coating layer, and an oxide layer formed on a surface portion of the Fe-Ni-Zn-O film. The method comprises providing an electrolyte of an acidic sulfate aqueous solution, carrying out an electrolysis treatment in the electrolyte under a current density ranging from 1 to 150 A/dm2, and carrying out an oxidation treatment to a surface of the zinciferous coated steel sheet. |