泡生法蓝宝石不同生长阶段热应力的数值模拟研究

Study on Numerical Simulation of Thermal Stress at Different Stages in Kyropoulos Sapphire Crystal Growth

利用计算机模拟对泡生法蓝宝石单晶各生长阶段的热应力进行了分析,发现晶体中最大热应力位于籽晶与新生晶体交界处或靠近固液界面的晶体边缘,其次位于晶体肩部。在此基础上,针对某一生长阶段讨论了加热器位置和坩埚形状对晶体中热应力分布的影响。结果表明:固液界面处的热应力随着加热器轴向中点与熔体轴向中点的距离L的增加先减后增,当L为190mm时,晶体中热应力最小;随着坩埚底部倒角半径的增加,固液界面处热应力呈上升的趋势。

The thermal stresses in KyropouIos sapphire crystal growth were studied using CGSim software. Through numerical analysis, it is found that the maximum thermal stress always exists in the seed-crystal interface, and along the melt/crystal interface, the next is at shoulder location. As the distance between the mid-point of the heater height and the mid-point of the melt inside the crucible, L, increases, the thermal stress along the melt/crystal interface first decreases and then increases. When L is 190mm, the thermal stress is minimum. As the radius of cur- vature of crucible bottom corner increases, the thermal stress alon~ the melt/crvstal interface alan increases.