| 摘要 |
The invention provides a surface pretreatment fluid for the metal substrate to be coated by cationic electrodeposition which makes it possible to attain satisfactory throwing power in the electrodeposition and which is excellent in corrosion inhibition performance. A surface pretreatment fluid for the metal to be coated by cationic electrodeposition which contains zirconium ions, copper ions and other metal ions and has a pH of 1.5 to 6.5, wherein the above other metal ions are at least one kind of ions selected from the group consisting of tin ion, indium ion, aluminum ion, niobium ion, tantalum ion, yttrium ion, and cerium ion, and the zirconium ion concentration is 10 to 10000ppm with the concentration ratio of copper ion to zirconium ion and that of other metal ion to copper ion being 0.005 to 1 by mass and 0.1 to 1000 by mass respectively. |
