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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/75083

    Title: KY法生長大尺寸氧化鋁單晶過程之 數值模擬分析;Numerical Simulation of Large-Size Sapphire Crystal during the Kyropoulos Process
    Authors: 莊效存;Chuang, Hsiao-Tsun
    Contributors: 機械工程學系
    Keywords: 泡生法;藍寶石長晶;數值模擬
    Date: 2017-08-16
    Issue Date: 2017-10-27 16:19:17 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 泡生法(Kyropoulos method, KY)是目前工業長晶中最大量被使用的長晶方法,因為其生長出來的晶體,溫度梯度較其他長晶法低,也因此較適合拿來生長較大尺寸的晶體;受限於KY爐體的設計,而無法直接觀察生長晶體的完整過程,且直接進行實驗量測,將會耗費許多時間及金錢,因此本研究使用以有限元素法(FEM)為基礎的套裝模擬軟體COMSOL Multiphysics,針對藍寶石晶體生長,模擬分析整個長晶過程的熱流場以及熱應力的分佈。
    ;The Kyropoulos method (KY) is the most common crystal growth method used in the industrial manufacturing large size crystal, because the crystal with this method has lower temperature gradient, and therefore it is more suitable for the larger size crystal growth. It is not easy to observe the complete process of crystal growth directly because of the design of KY furnace. Moreover, experimental measurement will spend a lot of time and money, so this study uses COMSOL Multiphysics which is the finite element software based on the theories of thermal and fluid dynamics. With this software, we tried to simulate the whole process of sapphire crystal growth, and analysis the phenomenon of crystal growth.
    The results show that with the growth of crystal, the maximum thermal stress can be divided into three stages: crown stage, body stage and tail stage. At crown stage, the maximum thermal stress increases as the length of crystal increases. And at body stage, the maximum thermal stress decreases as the length of crystal increases. The last stage, because the crystal is closer to the bottom of the crucible, so at tail stage, the maximum thermal stress increases as the length of crystal increase.
    By adjusting the speed of different heater power, it can be found that if the heater power decreases faster, the crystal crown shape will be flat, and the maximum thermal stress will be larger. On the other hand, if the heating power decreases slower, the crystal crown shape will be relatively steep, and thermal stress will be relatively smaller.
    The study also explored the effect of the different furnace structures, such as different size thermal shield and different crucible shape, which also effect the quality of crystal .
    Appears in Collections:[機械工程研究所] 博碩士論文

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