| 摘要 |
PURPOSE:To produce a titled steel plate of superior performance for preventing the formation of zinc white rust by treating the surface of a zinc hot dipped steel plate with an alkali soln. contg. H2O2 then treating the surface thereof with a chromate treating soln. contg. all Cr, Cr<3+>, PO4<3->, SiF6<2->, respectively at prescribed ratios. CONSTITUTION:The surface of a zinc hot dipped steel plate is treated with an alkali soln. contg. 0.05-0.2mol/l H2O2 and is activated by removing inert films of Al oxide and the like. Next, the activated surface of said plated steel plate is treated with a water base chromate treating soln. contg. 18-30g/l all Cr, 35-60% Cr<3+> based on the content of all Cr, 7-15g/l PO4<3->, 1-6g/l SiF6<2->. Namely, the tendency to coloring that occurs in the case of treatment with a CrO3-weak acid- silicofluoride type treating soln. is suppressed by the activation treatment with the H2O2-contg. alkali soln., and the bright surface gloss, beauty and appearance are assured; in addition, the marked improvement in rust preventive property is obtained. |
