| 摘要 |
PURPOSE:To obtain a titled plated steel sheet in the stage of forming preliminarily an Ni coating layer on the steel sheet and subjecting the steel sheet to metal hot dipping by an oxygen free furnace method by specifying the quantity of Ni plating, drying temp. and the atmosphere in a heating furnace. CONSTITUTION:A black sheet for plating (steel sheet) which is cleaned by an ordinary pretreatment is formed thereon with a coating layer of Ni or Ni alloy at 0.002-1.5g/m<2> coating weight per side by an electroplating method, chemical plating method or coating of an Ni ion-contg. soln., etc. Such coated steel sheet is dried at <=150 deg.C in succession thereto and is subjected to a heating treatment in an indirect heating furnace. The steel sheet is treated in the atmosphere in the furnace of an inert gas such as N2 or Ar having <=-35 deg.C dew point and extremely low moisture content or an inert gas consisting of <=10% H2 in order to prevent the oxidation of the coating layer and to prevent the intrusion of the gaseous H2 into the coating layer. The coated steel sheet heated in the oxidation free state in the above-mentioned manner is passed through a metal hot dipping bath of Zn, Al, etc. without being exposed to the atm. |
