Patent ID: 9157165
Filing Date: 2015-10-13
Classification: C25D

Abstract:
1. A method of production of a chemically treated steel sheet, comprising: continuously supplying a steel strip into a treatment solution containing zirconium ions and fluorine ions and treating the steel strip by cathode electrolysis in the treatment solution containing zirconium ions and fluorine ions to form a chemically treated coating containing zirconium on the steel strip, resupplying zirconium ions in the treatment solution with at least two compounds, wherein the at least two compounds are selected from the group consisting of a fluorine compound and a different compound which is not a fluorine compound, wherein the fluorine compound is selected from the group consisting of a compound including zirconium and fluorine, and zirconium fluoride, and wherein the different compound which is not a fluorine compound is selected from the group consisting of zirconium halides, zirconium hydroxide, zirconium carbonate, zirconium ammonium salts, zirconium nitrate, zirconium sulfate and zirconium acetate, during the cathode electrolysis to maintain the zirconium ions in the treatment solution at 0.05 to 30 g/liter, to maintain the fluorine ions in the treatment solution at 0.5 to 10 times the content of the zirconium ions, and to maintain each kind of ion, other than the zirconium ions and the fluorine ions, derived from the fluorine compound and the different compound which is not a fluorine compound, in the treatment solution at not more than 10 times the content of the zirconium ions, wherein the ions other than the zirconium ions and the fluorine ions, derived from the fluorine compound and the different compound which is not a fluorine compound, are selected from the group consisting of chlorine ions, bromine ions, iodine ions, hydroxide ions, carbonate ions, ammonium ions, nitrate ions, sulfate ions and acetate ions, and wherein the amount of resupplied solution is an amount corresponding to the amount of the treatment solution taken out by the steel strip.