| 摘要 |
PURPOSE:To obtain a galvanizing steel plate which is excellent in black change resistance, corrosion resistance and a painting property by performing galvanization to a steel plate, bringing its surface to alkali treatment, and thereafter, precipitating Ni or a specified quantity to the surface in an aqueous solution containing Ni ions, and subsequently, executing chromate treatment, and making Cr of a specified quantity adhere. CONSTITUTION:A Zn or Zn-Al molten plating is performed for a steel plate, its surface is washed by an alkali solution, Al segregated on the surface layer is dissolved selectively, Al on the dead surface layer is decreased, and the purity of Zn is made high thereby. Subsequently, Ni of 1-50mg/m<2> is precipitated on the surface of the steel plate, in an aqueous solution containing Ni ions such as a watt bath for electric plating, etc., and subsequently, chromate treatment is executed, and Cr is made to adhere within a range of 5-60mg/m<2>. Also, even if Ni ions are contained in said alkali solution, and dissolution of Al and precipitation of Ni are executed simultaneously, an equal effect is obtained. |
