| 摘要 |
PURPOSE:To prevent the development of streak and to improve the yield of product by specifying the melting point and viscosity of powder adding on the molten metal surface. CONSTITUTION:The powder 14 having <900 deg.C the melting point and <5 poise the viscosity at 1,300 deg.C, is added on the molten metal surface in the mold 11. The powder 14 is melted on the molten surface and easily flowed into the gap between the solidified shell 16 and the mold 11 and so bubble existing between the solidified shell 16 and the mold 11 is extremely decreased. And, the thermal conductivity between the mold 11 and the solidified shell 16, the cooling velocity for the molten metal and the solidified shrinkage of the molten metal are increased. In this way, fear of lapping for the solidified shell 16 in the mold 11 is decreased and the development of streak is prevented. |
