| 摘要 |
PURPOSE:To produce a blackened steel sheet of high quality with the existing cathodic treatment facilities without restricting the kind of steel sheet used by cathodically treating the surface of a steel sheet at a specified current density in a bath of a specified pH contg. Zn and Ni ions. CONSTITUTION:The surface of a steel sheet is cathodically treated at 0.5-5A/dm<2> current density in a conventional Zn-Ni alloy plating bath of 5.3-5.8pH contg. >=about 50g/l Ni ions to produce a blackened steel sheet. The treatment temp. is desirably regulated to about 50-60 deg.C, the thickness of the resulting black layer depends on the treatment time, and the kind of steel sheet used is not especially restricted. A blackened steel sheet of high quality is easily produced.
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