Abstract: 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, solid-liquid 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.

Key words: 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, solid-liquid 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.