| 摘要 |
PROBLEM TO BE SOLVED: To provide a chromate solution composition for manufacturing a chromated galvanized steel sheet having satisfactory corrosion resistance and uniform white external appearance. SOLUTION: In this solution, Cr concentration is 15-80 (g/l) expressed in terms of metal chromium, and further, as reducing agents, concentrations of ethylene glycol and glycerine are 0.1-0.25 (TCr) and 0.1-0.25 (TCr), respectively, and their total concentration is regulated to 0.2-0.4 (TCr), wherein, when A (g) represents the charge weight of ethylene glycol or glycerine or their total charge weight and B (g) represents the charge weight of chromic acid, TCr=A /(B×0.52) is satisfied. This chromate solution is agitated until the value of Cr3+/(Cr3++Cr6+) becomes 0.6-0.8 and then applied to a galvanized steel sheet, followed by drying by heating.
|
