| 摘要 |
PURPOSE:To form excellent plating film on steel hoop, by adjusting the surface of the bath in a molten metal tank by moving vertically the metal-melting tank, the bath surface of which is opened to the air, and by charging the molten metal while degassing the molten metal. CONSTITUTION:Zinc is charged to a metal-melting tank 1 and is melted. The melting tank 1 is lifted so as to dip an ascending pipe 5 and a descending pipe 6 into the bath. A vacuum degassing chamber 4 is heated with a heaing plate 11 and evacuated to about 10<-5> Torr. The height of the bath surface 12 is made equal to that of a continuing pipe 8, and degassing is performed by charging e.g. Ar gas through a conduit 7. A vacuum evaporation chamber 9 is evacuated, the molten zinc is charged through the continuing pipe 8 to a molten metal tank 15 by lifting the melting tank 1. The vacuum evaporation tank 9 is kept at about 10<-5> Torr. Molten zinc accommodated in the molten metal tank 15 and the continuing pipe 8 is heated and kept at the temp. Vapor coating of a substrate 17 with zinc allows to manufacture excellent plating film nearly free of oxide. |
