ELECTROLYTIC CHROMATE TREATMENT OF GALVANIZED STEEL SHEET WITH HIGH WHITENESS DEGREE AND EXCELLENT CORROSION RESISTANCE

摘要

PURPOSE: An electrolytic chromate treatment of galvanized steel sheets with high whiteness degree and excellent corrosion resistance is provided. CONSTITUTION: The electrolytic chromate treatment of galvanized steel sheets is characterized in that chromate solution contains 3 to 50g/L of Cr (trivalent chromium+hexavalent chromium), 0.1 to 5g/L of nitric acid and 0.05 to 0.5g/L of boric acid; pH range of the chromate solution is 0.5 to 5; the temperature of the chromate solution is 20 to 60C; and current density applied to the chromate solution is 1 to 40 A/dm¬2.