SPRAYING SOLUTION FOR MANUFACTURING OF MINISPANGLE MOLTEN ZINC COATED STEEL SHEET

摘要

A spraying solution for minimizing a spangle which comes into being on a surface of molten zinc coated steel in manufacturing process of molten zinc coated steel consists of 0.5-5 wt.% of water soluble inorganic salt and 0.001-10 wt.% of water soluble polymer. In an example, a steel is passed through a plating bath having a composition of 0.2% Al, 0.1% Pb, Zn and others with a temperature of 460 deg.C and sprayed with a spraying solution, which is composed of 1.9 wt.% of ammonium phosphate and 0.1 wt.% of sodium pyrophosphate as an inorganic salt and 0-20 wt.% of polyvinylpyridinium chromate as a water soluble polymer. The surface roughness and glossiness of molten zinc coated steel is good, when a concentration of a water soluble polymer in a spraying soluton is 1-5 wt.%