热屏间距对泡生法蓝宝石单晶生长影响研究

Effect of the Heat-shield Spacing on the Crystal Growth of Kyropoulos Sapphire

太空、军事和科研等高科技领域的持续发展极大促进了对蓝宝石晶体的需求,泡生法是蓝宝石晶体的主要制造方法之一;热场结构对所得蓝宝石晶体的质量具有重要影响。本文对采用泡生法工艺制造蓝宝石单晶过程中,具有内置7层氧化锆外置8层钼金属的新型热屏结构间距进行研究。通过数值模拟考察热屏间距对单晶炉功率、固-液界面形状和晶体热应力的影响确定了合理的热场结构;并与试验生产结果进行对比验证。结果表明:热屏间距增大使得单晶炉功率明显提升,并引起固-液界面凸度增大;而蓝宝石晶体热应力出现减小。综合考察三个影响因素的影响,最后确定热屏间距为5 mm时单晶炉能耗较低,可用于制造高质量的蓝宝石晶体。

The continuous development of high technology in the field,such as the deep-space,military and scientific research,has greatly promoted the demand for sapphire crystals. Kyropoulos method is one of the main manufacturing methods of sapphire crystal; the thermal field structure has an important influence on the quality of sapphire crystal. This paper studies the spacing of the new heat-shield structure with 7 internal layers of zirconia and external 8 layers of metallic molybdenum in the process of manufacturing sapphire. The influence of heat-shield spacing on the power consumption,solid-liquid interface shape and crystal thermal stresses of single crystal was investigated by numerical calculations;the reasonable heat-shield structure was determined. The results were compared with the experimental results. It show that the power consumption of growth furnace is obviously improve with the increase of heat-shield spacing,and cause the solid-liquid interface convexity increase,as well the Von-Mises stress decrease. Consideration of the co-exerted effects of heat-shield spacing on the power consumption,solidliquid interface shape and crystal thermal stress,the optimal heat-shield spacing is determined as 5 mm,which resulted in the lowest energy consumption,and could implement to fabricate high quality sapphire crystal.