| 摘要 |
PURPOSE:To improve the adhesion of a painted film formed on a steel sheet at a high temp., service, the corrosion resistance and workability of the steel sheet by previously forming an Ni layer of a specified thickness on the surface of the steel sheet by plating and a specified amt. of a chromate film on the Ni layer by electrolysis. CONSTITUTION:An Ni layer of >=0.4mum, preferably 0.4-2mum thickness is formed on the surface of a steel sheet as an underlayer for heat resistant coating by plating such as electroplating. A chromate film is then formed on the Ni layer by electrolysis by >=10mg/m<2>, preferably 10-100mg/m<2> (expressed in terms of Cr). When a painted film is formed on the steel sheet for heat resistant coating having the resulting composite film, the adhesion of the painted film can be kept high even during use at a high temp.
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