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  本文關(guān)鍵詞： 微下拉法 晶體生長 感應(yīng)加熱 全局模擬　出處：《重慶大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：本文基于有限體積法對微下拉法生長YAG晶體進行包括感應(yīng)加熱在內(nèi)的全局數(shù)值模擬,并分析各參數(shù)對生長爐內(nèi)溫度場和坩堝產(chǎn)熱的影響。建立微下拉法晶體生長全局數(shù)學(xué)物理模型,模型中耦合了感應(yīng)加熱、氣體與熔體對流以及固液氣三相的熱輸運,熔體中對流同時考慮浮力與表面張力作用。為統(tǒng)一使用有限體積法離散控制方程,采用復(fù)函數(shù)法求解電磁場,并與流函數(shù)法對比驗證了程序的正確性。并分析了整個生長爐內(nèi)的溫度場和流場(包括氣體和熔體)分布。由于晶體結(jié)晶速率主要受固液交界區(qū)溫度梯度影響,尤其是軸向溫度梯度。為優(yōu)化晶體生長爐結(jié)構(gòu),本文詳細分析了線圈軸向和徑向位置、線圈匝數(shù)、通入線圈交流電大小和頻率大小以及改進后熱器材料對固液交界區(qū)溫度分布和溫度梯度的影響。結(jié)果表明:(1)隨著線圈向上移動,固液交界區(qū)溫度降低,固液交界區(qū)軸向溫度梯度增大。隨著線圈徑向距離增大,固液交界區(qū)溫度降低,而固液交界區(qū)軸向溫度梯度變化并無明顯規(guī)律,當(dāng)線圈徑向位置為80和85mm時,軸向溫度梯度明顯增大。隨著線圈匝數(shù)減小,固液交界區(qū)溫度降低。線圈匝數(shù)為4匝和6匝時,坩堝上的有效感應(yīng)區(qū)面積太小,產(chǎn)熱效率太低。(2)當(dāng)后熱器材料采用與保溫層相同的氧化鋯時,與原始模型相比溫度梯度增大,但此時固液交界區(qū)的溫度降低。當(dāng)不采用后熱器裝置時,溫度梯度明顯增大,但此時溫度大幅下降,加熱效率非常低,需增大線圈中通入的電流大小。(3)當(dāng)電流數(shù)值增大,爐內(nèi)溫度最大值隨之近似線性增長,浮區(qū)溫度也均勻增長。電流頻率增大,爐內(nèi)溫度最大值隨之而增大。頻率為1kHz-10kHz時,溫度急速增大。而頻率為20kHz-100kHz時,溫度增大平緩。電流頻率范圍為10kH-20kHz時加熱效率最高。本文所建模型能較真實地反映微下拉法的實際晶體生長環(huán)境,為優(yōu)化晶體生長爐結(jié)構(gòu)和生長工藝提供參考。
[Abstract]:Based on the finite volume method, the global numerical simulation of YAG crystals grown by micro-pull-down method, including induction heating, is carried out in this paper. The effects of various parameters on the temperature field and crucible heat generation in the growth furnace are analyzed. A global mathematical and physical model for crystal growth by micro-pull-down method is established. The model is coupled with induction heating, gas and melt convection, and the thermal transport of solid-liquid gas. Both buoyancy and surface tension are considered for convection in melt. In order to discretize the governing equation with finite volume method, the complex function number method is used to solve the electromagnetic field. Compared with the flow function method, the program is proved to be correct. The temperature field and the flow field (including gas and melt) in the whole furnace are analyzed. The crystal crystallization rate is mainly affected by the temperature gradient at the solid-liquid junction. Especially the axial temperature gradient. In order to optimize the structure of crystal growth furnace, the axial and radial positions of the coils and the number of turns of the coils are analyzed in detail in this paper. The effect of AC current and frequency on the temperature distribution and temperature gradient at the solid-liquid junction is studied. The results show that the temperature at the solid-liquid junction decreases with the moving of the coil. The axial temperature gradient at the solid-liquid junction increases with the increase of the radial distance between the coils, but the axial temperature gradient at the solid-liquid junctions does not change regularly. When the radial position of the coils is 80 mm and 85 mm, the axial temperature gradients of the solids and liquid junctions decrease with the increase of the radial distance of the coils. The axial temperature gradient increases obviously. With the decrease of the number of coils, the temperature at the solid-liquid junction decreases. When the number of coils is 4 turns and 6 turns, the effective induction area on the crucible is too small. The thermal efficiency is too low. (2) when zirconia with the same insulation layer is used, the temperature gradient increases compared with the original model, but the temperature at the solid-liquid junction decreases. When the rear thermostat is not used, the temperature gradient increases obviously. However, when the current value increases, the maximum temperature in the furnace increases linearly, and the temperature in the floating zone increases uniformly, and the current frequency increases. The maximum temperature of the furnace increases rapidly when the frequency is 1kHz-10kHz, and the frequency is 20kHz-100kHz. The heating efficiency is the highest when the current frequency range is 10kH-20kHz. The model in this paper can reflect the actual crystal growth environment of micro-pull-down method and provide reference for optimizing the structure and technology of crystal growth furnace.
【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：O782

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本文編號：1538583