Numerical simulation during vacuum sublimation purification of metal Tm (I): model foundation and validation

The thermo physical parameters of Tm vapor and the range of sublimation temperature were determined by vapor pressure of metal Tm, and a 2-D axis-symmetric heat transfer model was developed to investigate the temperature distribution in sublimation furnace. The simulation results showed that, due to the heat loss at crucible bottom, the temperature of crucible, solid metal and Tm vapor increased with crucible height increasing, reached the maximum value in the middle of crucible in height direction, and then decreased rapidly; at the outside surface of condenser, the temperature decreased sharply; with heating body temperature of 1000 °C, the mean temperature at upper surface of solid Tm was 22 °C higher than that on the lower surface, the mean temperature of upper surface of solid Tm was about 32 °C lower than that of heating body, and the calculated sublimation velocity was 8.16 g/cm2/h, which was only 54.4% of sublimation velocity calculation by heating body temperature.