Patent ID: 7914851
Filing Date: 2011-03-29
Classification: C23C,Y10T

Abstract:
1. A method of manufacturing a hot-dip galvanized steel sheet, comprising: preparing a steel sheet for hot-dip galvanization; dipping the steel sheet in a bath of zinc-coating solution containing 0.13 to 0.3% by weight of aluminum; air-wiping the steel sheet having the coating solution bound thereto, thereby removing an excess of the coating solution; spraying water or an aqueous solution onto the surface of the air-wiped steel sheet by two-fluid spray nozzles; using a steel sheet temperature in the range of a hot-dip galvanization temperature to 419° C. as a spray initiation temperature and using a steel sheet temperature in the range of 417° C. to 415° C. as a spray completion temperature; passing sprayed liquid droplets of water or aqueous solution through a mesh-like high-voltage charged electrode which is electrically charged with a high voltage of −1 to −50 kV applied by DC with an addition of a high voltage pulse; and allowing the electrode-passed liquid droplets to be bound to the surface of the steel sheet and thereby being served as solidification nuclei of molten zinc, wherein, among sprayed liquid droplets, the liquid droplets not bound to the steel sheet are kept from falling into the coating bath by air which is blown into an air curtain and are removed by a suction hood.