| 摘要 |
<p>The purpose of the present invention is to provide a replenisher which is capable of supplying Zr ions to a metal surface treatment solution, while suppressing an increase in the HF concentration in the metal surface treatment solution, so that a chemical conversion coating film can be continuously formed on a steel sheet by electrolysis. A replenisher of the present invention is a replenisher which is used for the purpose of supplying zirconium ions to a metal surface treatment solution that contains zirconium ions and fluorine ions, and the replenisher contains (A) zirconium hydrofluoric acid or a salt thereof and/or (B) hydrofluoric acid or a salt thereof and (C) a fluorine-free zirconium compound. The total concentration (g/l) of zirconium ions derived from the components (A) and (C) is 20 or more, and the ratio of the total molar amount (M F ) of the fluorine ions derived from the components (A) and (B) relative to the total molar amount (M Zr ) of the zirconium ions derived from the components (A) and (C), namely M F /M Zr is 0.01 or more but less than 4.00.</p> |
