METHOD FOR DETECTING DROSS IN HOT DIP GALVANIZING LAYER BY ELECTROCHEMICAL METHOD

摘要

PURPOSE: A method for detecting dross in hot dip galvanizing layer by electrochemical method is provided to improve productivity by promptly detecting dross adhered to galvanized steel sheet and steel wire, thereby immediately controlling plating process and suppressing plating defects generated during secondary processing. CONSTITUTION: The method comprises the steps of preparing a hot dip galvanized steel sheet or steel wire cut to proper size; dipping the hot dip galvanized steel sheet or steel wire into an aqueous solution in which 0.1 to 2.0 mL of sulfuric acid, 0.1 to 2.0 mL of nitric acid, 0.5 to 5 mL of hydrogen peroxide and 1 L of distilled water are mixed; conducting power supply voltage of 5 to 20 V and 20 to 200 mA to the anode of the hot dip galvanized steel sheet or steel wire and the cathode of stainless steel sheet for 5 to 40 minutes; cleaning the surface part of electropolished galvanized steel sheet or steel wire using ethyl alcohol; and observing residual dross on the surface of galvanizing layer of the galvanized steel sheet or steel wire by an optical microscope, wherein dross in the galvanizing layer has superior corrosion resistance compared with zinc matrix so that dross formed in a projected shape is easily detected by the optical microscope.