| 摘要 |
PURPOSE:To form a Zn alloy plating layer having high adhesion strength by a hot dipping method without generating a non-plated part in the stage of hot dipping various steel parts with Zn alloy by treating preliminarily the parts with an aq. soln. of a flux compsn. having a specific compsn. CONSTITUTION:A steel product to be plated is first cleaned by alkali degreasing, pickling and rinsing in the stage of forming a Zn alloy plating layer having high resistance to corrosion by a hot dipping method on the surface of a steel plate, steel pipe, steel wire, shape steel or steel formed article. The steel product is then dipped in an aq. soln. contg. a flux composed of 0.3-8.0% SnCl2, 0.3-8.0% acidic fluoride such as NH4HF2, NaHF2, KHF2 or the like, 5-30% alkali chloride such as NaCl, KCl or the like and the balance ZnCl2 at 200-300g/l concn. and is then pulled up and is dried. The product is dipped in a plating bath of a Zn alloy contg. 3.5-5% Al, 0.02-0.5% Si and 0.01-0.05% Mg kept at 450- 480 deg.C to form a plating layer of the corrosion-resistant Zn alloy having high adhesion without a non-plated part. |
