Patent ID: 9169577
Filing Date: 2015-10-27
Classification: B32B,C21D,C22C,C23C,C25D,Y10T

Abstract:
1. A method for manufacturing a surface-treated steel sheet, comprising forming a corrosion-resistant coating comprising at least one layer selected from a Ni layer, a Sn layer, an Fe—Ni alloy layer, an Fe—Sn alloy layer, and an Fe—Ni—Sn alloy layer on at least one side of a steel sheet; and forming an adherent coating by cathode electrolytic treatment in an aqueous solution containing Zr in a concentration of 0.008 to 0.07 mol/L (L: liter) and at least one species selected from phosphoric acids and phenolic resins in a total molar ratio to Zr of 0.01 to 10 under electrolysis conditions where a current is used that varies between a current density at which Zr precipitates and a current density at which no Zr precipitates at a period of 0.01 to 0.4 second and that remains within a current density range where no Zr precipitates for 0.02 to 0.05 seconds per period, and the number of cycles is 10 or more, wherein the upper limit of the current density range where no Zr precipitates depends on the composition and pH of the aqueous solution used for the cathode electrolytic treatment.