BLACKENED RUSTPROOF STEEL SHEET AND ITS MANUFACTURE

摘要

PURPOSE:To manufacture stably a blackened rustproof steel sheet in a short time without aging a treating soln. or causing environmental pollution due to waste liquor by plating the surface of a steel sheet with Zn and forming a Zn- Ni alloy layer on the plated surface. CONSTITUTION:At least one side of a steel sheet is plated with Zn or a Zn alloy to form one or more layers as an inner layer. A Zn-Ni alloy layer contg. >=15wt% Ni is formed on the inner layer as a surface layer by >=0.01g/m<2> by carrying out electrolysis using the steel sheet as a cathode and an insoluble anode as a counter electrode at <=40A/dm<2> current density in an acidic aqueous soln. of <=3pH contg. Ni<2+> and Zn<2+>. Thus, a blackened rustproof steel sheet is stably obtd. in a short time such as about several - several ten sec.