| 摘要 |
PURPOSE: To produce a Zn dispersion plated steel sheet excellent in low temp. chipping resistance and bare corrosion resistance by using a plating bath contg. a surfactant contg. Zn, Cr, nitrogen and fluorine, an alumina sol and a silica sol and applying a steel sheet to plating at a specified temp. and current density. CONSTITUTION: A plating bath contg. Zn<2+> by 50 to 200g/L as Zn concentration, Cr<3+> by 30 to 80g/L as Cr concentration, 1 to 5g/L surfactant contg. nitrogen and fluorine of 700 to 50000 molecular weight as an organic additive and 1 to 50g/L alumina sol and/or silica sol is prepd. By using the same plating bath, on at least one side of a steel sheet, a galvanizing layer of 10 to 50g/m<2> coating weight is formed at 40 to 180A/dm<2> and 40 to 70 deg.C bath temp. This plating layer contains, by weight, 0.1 to 8% metallic Cr, 0.1 to 10% oxide Cr and 0.05 to 8% oxide or hydroxide of Al and Si. Moreover, this plating layer is constituted of aηsingle phase.
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