CHROMATE SOLUTION FOR SURFACE TREATMENT OF ZINC-PLATED STEEL SHEET

摘要

PURPOSE: A chromate solution for surface treatment of zinc-plated steel sheet is provided to give superior corrosion resistance in processed part and beautiful appearance. CONSTITUTION: The chromate solution comprises Cr 5-130g/L·water; phosphate ion(PO4¬3-) 5-80wt.% based on the weight of Cr; fluorine ion 1-10wt.% based on the weight of Cr, tungsten ion 2-50wt.% based on the weight of Cr; colloidal silicon oxide 2-20wt.% based on the weight of Cr. Herein, the portion of trivalent chromium(Cr¬+3) to total chromium is 0.3 to 0.7.