METHOD FOR MANUFACTURING A MOLTEN ZINC COATING STEEL PLATE WITH AN EXCELLENT CORROSION RESISTANT MINISPANGLE

摘要

The mini-spangled molten galvanized steel sheet is produced by (1)spray treatment of a phosphate aqueous solution on the surface of the steel sheet as a starting material, under galvanizing process or just before the solidification of molten zinc on the surface of the steel sheet, (2)endothermic reaction of phosphate ion, and (3)refinement of spangle to the diameter of below 100 Pm. The optimum conditions of mini-spangle treatment are as followw : (a)an aqueous solution for mini-spangle treatment is soluble phosphate, Co3(PO4)2 of about 1 to 5 wt.%, and (b)amounts of spray solution are about 50 to 100 g/m2. The disclosed steel sheet having good corrosion resistance and good coating adherency is used for automobile and various kinds of household etc.