| 摘要 |
PURPOSE:To obtain good guality cast slab which is free from any surface defects such as longitudinal cracking by applying the Ni or Cr porous plating of the specified voids on the inside surface of a water-cooled copper mold and regulating the heat removal rate of this mold to the specified value or less. CONSTITUTION:Porous plating of Ni or Cr of voids 30-10vol% as a heat insulating layer is applied to thicknesses of 0.3-3mm. on the inside surface of the water- cooled copper plate and the heat removal rate is regulated to 0.81X10<6>Kcal/m<2>.h or less. To make this porous plating, first ordinary plating is applied on the object to be plated as negative pole, thence etching is done with the object to be plated as positive pole to form fine pits on the plating surface. Finally, again with the object to be plated as negative pole, strong current of pulse form is flowed to this to complete plating. Namely, the firm heat insulating layer of high endurance and heat resistance is readily formed by the employment of this porous plating and the quality of the cast slab may be improved by using this mold. |
