| 摘要 |
A ceramic mould is supported on a stainless steel platform carried at the upper end of a water-cooled tube surrounded by a copper cylinder containing alumina powder of approximately 100 mu m particle size which is fluidized by an inert gas. Metal in the mould is melted by a furnace which surrounds the mould and the mould is progressively withdrawn into the fluidized bed by which heat is extracted and transferred to water cooled coils surrounding the copper cylinder. In a modification, the inert gas is drawn from the fluidized bed by way of a filter and vacuum pump whereby the outlet pressure is reduced to about 1 torr. This reduces the risk of contamination of the alloy and permits re-use of expensive cooling gases. |
