| abstract |
PURPOSE:To easily produce a black band steel having excellent characteristics by electrolyzing a band steel as the cathode in an aq. acidic soln. contg. Zn<2+> and >=1 kind among Fe<2+>, Co<2+>, and Ni<2+> and further contg. an oxidizing ion and a thioic compd., and then applying chromating and guard coating to the steel. CONSTITUTION:A band steel or a galvanized band steel or a Zn alloy plated band steel is used as the cathode, and electrolyzed in an aq. acidic soln. having the composition as described later with the use of a Pb anode. Chromating and guard coating are then applied to produce a black band steel having excellent appearance and corrosion resistance. The aq. soln. for electrolyzing the band steel contains Fe<2+>, Co<2+>, and Ni<2+> in addition to Zn<2+> or further metallic ions such as Cr<3+>, Pb<2+>, and Ag<2+> as the essential components and further contains an oxidizing ion such as NO and Clo<-> and a thioic compd. such as a thiosulfate. The soln. is kept at 1.5-3.0pH and 20-80 deg.C, and used. Resins, inorg. polymers, oil, wax, etc., are used for the guard coating. |