| 摘要 |
A nickel and/or cobalt deposition process which can be run at a nearly neutral pH and which rapidly deposits nickel and/or cobalt in quantities large enough to improve the paint adhesion and post coating corrosion resistance and which has a good solution stability, is achieved by treating zinc coated sheet steel with an aqueous solution that has a pH between 5 and 10 inclusive and comprises (A) a total of at least 0.01 g/L of metal ions selected from the group consisting of NI<2+> and Co<2+> ions and (B) a sufficient amount to fully complex the metal ions recited in part (A) of complexing agents selected from the group consisting of ammonia and organic compounds having at least one amino group in the neutral region. The substitution precipitation reaction of nickel and cobalt is substantially accelerated by the presence, as a third component in addition to the metal ion and complexing agent, of at least one ionic species or compound selected from the nitrite ion, nitrate ion, thiocyanate ion, thiosulfate ion, thiourea, phosphite ion, hypophosphite ion, and perchlorate ion. |
