| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a surface-treated steel sheet, which is economically advantageous and allows stable formation of a metal oxygen compound film in a sufficient amount on a steel sheet.SOLUTION: The method for manufacturing a surface-treated steel sheet comprises immersing a steel sheet in an electrolytic treatment solution containing at least one metal ion of Zr and Al to continuously carry out an electrolytic treatment to form a film essentially comprising an oxygen compound film containing the above metal on the steel sheet. The method for manufacturing a surface-treated steel sheet includes a reverse osmosis membrane treatment step in which the electrolytic treatment solution is partially extracted and guided to a reverse osmosis membrane to remove a component that inhibits formation of the film when the amount of the component is excessive, as a permeated solution containing the component that inhibits formation of the film when the amount of the component is excessive, thereby obtaining a concentrated solution with concentrated metal ions of the above metal, and the concentrated solution is returned to the electrolytic treatment solution.SELECTED DRAWING: Figure 1 |
