| 摘要 |
PURPOSE:To provide corrosion resistance of the treated surface of a phosphated automobile body, corrosion resistance after painting and coated film adhesiveness by subjecting said automobile body to a cathodic electrolyzing treatment with a chromate treating liquid having specific characteristics. CONSTITUTION:The automobile body to be painted by cationic electrodeposition painting, etc., is first subjected to surface cleaning by an alkaline cleaning agent, then to washing followed by conditioning by a surface conditioning agent and thereafter, a phosphate film is formed thereon. The phosphated automobile body is subjected to the cathodic electrolyzing treatment with the chromate treating liquid contg. 0.05-10.0g/l Cr<6+> ions and having <=1.0 weight ratio of Cr<3+> ions/Cr<6+> ions. The automobile body is thereafter subjected to washing and draining and drying at need without demineralizing washing, then the cationic electrodeposition painting is started. The excellent corrosion resistance and painting adhesiveness are thus provided to the surface of the automobile body.
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