共查询到18条相似文献,搜索用时 156 毫秒
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蓝宝石晶体因优异的综合性能被广泛用于航空航天等高性能要求领域.泡生法是目前生产大直径蓝宝石单晶的主要方法,热场对生产工艺、产品质量和单晶炉功率具有重要影响;并将影响生产成本.本文对氧化锆及钼金属组合式热屏中氧化锆材料内置、外置及材料不同组合方式对泡生法蓝宝石单晶炉功率的影响进行研究,得到合理的热场结构;并与实际生产结果进行验证.结果表明:相比于传统的15层钼保温结构,加入氧化锆保温层会明显降低单晶炉能耗,其中氧化锆内置的热场结构对单晶炉能耗降低影响更为明显;随着氧化锆层由0增加至15层,单晶炉能耗显著降低,相比传统15层钼保温结构,15层氧化锆保温结构炉体功率降低了38;. 相似文献
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泡生法生长蓝宝石单晶的热场改进与模拟优化 总被引:2,自引:1,他引:1
在泡生法蓝宝石单晶生长中,单晶炉内的热场对晶体质量至关重要.本文首先对单晶炉的顶部热屏、环形加热器和炉底保温进行了改进,然后结合计算机数值模拟,对热场改进前、后晶体的轴向和径向温度梯度、晶体表面温度分布、加热器功率等进行分析对比.结果表明:改进后的倾斜热屏增强了单晶炉内的辐射传热,对已生长出的晶体起到了后热作用,降低了晶体内的热应力;对加热器和底部钼保温层的改进,减小了加热器与坩埚间的热阻,增强了炉内的保温作用,使加热功率降低了约8%. 相似文献
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在泡生法蓝宝石单晶生长中,固液界面形状对晶体生长质量影响极大.本文针对泡生法蓝宝石晶体生长进行数值模拟,研究了晶体半透明性、放肩角、底部钼屏保温层厚度、加热器侧部和底部功率分配比等对固液界面形状的影响.模拟结果发现:不考虑蓝宝石晶体的半透明性,则固液界面凹向熔体生长,反之则固液界面凸向熔体生长;放肩角增大、底部钼屏保温层增厚,都造成固液界面凸度减小;加热器侧部与底部的功率比增大,则固液界面凸度增大.实际的固液界面形状取决于多种参数的综合作用. 相似文献
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针对泡生法蓝宝石单晶生长的不同生长阶段的温场、流场和固液界面形状进行数值模拟研究.并分析了加热器相对坩埚的轴向位置和不同生长速率对蓝宝石单晶生长的影响.结果表明:在蓝宝石单晶生长中,在靠近坩埚壁面和固液界面的熔体内,等温线密,温度梯度较大;在靠近坩埚底部的熔体内,等温线稀疏,温度梯度较小.随着晶体高度的增加,熔体对流由放肩阶段的两个涡胞变成等径阶段的一个涡胞,熔体平均温度有小幅度下降;加热器相对坩埚的轴向位置对晶体生长炉内温场和固液界面形状影响很大,随着加热器位置上移,晶体内平均温度升高,温度梯度减小;熔体内平均温度降低,温度梯度增大.同时固液界面凸度增大.随着晶体生长速率增大,固液界面凸度增大,界面更加凸向熔体. 相似文献
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泡生法蓝宝石晶体炉内保温屏是炉内温场的重要部件,并对晶体生长有重要影响.本文对不同的保温屏材料的影响进行了计算分析.通过分析加热功率、晶体温度分布、固液界面形状,比较钨钼、石墨、氧化锆三种材料的保温屏的保温性能和对晶体生长的影响,结果表明:氧化锆保温性能优于钨钼保温屏,而石墨保温性能最差.选用钨钼保温屏和氧化锆保温屏晶体温度分布较为接近,且高于选用石墨保温屏时的温度分布.石墨保温屏对应的固液界面形状最大,钨钼屏其次,而氧化锆材料时形状最平缓. 相似文献
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采用有限元法,对泡生法生长蓝宝石晶体不同生长阶段固液界面的形状和温度梯度进行模拟计算,探讨分析了生长速率对放肩、等径阶段蓝宝石生长的影响.结果表明:固液界面凸出度在放肩阶段较大,在等径阶段凸出度相对较小,固液界面温度梯度随着晶体生长不断减小.在合理速率范围内,放肩阶段0~2 mm/h,速率对固液界面的影响很小,等径阶段2~5 mm/h,速率对固液界面的影响越来越大,固液界面温度梯度和形变均随速率的增大而减小.利用模拟结果,调节实际晶体生长工艺参数,成功长出80 kg的大尺寸高质量蓝宝石晶体. 相似文献
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在CZ法生长太阳能级单晶硅中,单晶炉的导流筒、热屏和炭毡对晶体生长有很大影响.通过对上述三个部件进行改进优化,并通过数值模拟对优化前后晶体和熔体的热场、热屏外表面与石英坩埚内壁面之间的氩气流场以及晶体中的热应力进行分析,得出以下结论:石墨导流筒的引入减少了炉体上部的氩气流动涡胞,进而减少了SiO在单晶炉上部的沉积;优化后的热屏减少了加热器对晶体的烘烤,使结晶速率加快;优化后的侧壁炭毡阻止了加热器向上部的热损失.优化后在加热器功耗不变时,结晶速率至少可提高35;,而不增加宏观位错的发生概率. 相似文献
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蓝宝石晶体热性能的各向异性对SAPMAC法晶体生长的影响 总被引:1,自引:1,他引:0
采用有限元法对冷心放肩微量提拉法蓝宝石晶体生长过程中晶体内的温度、应力分布进行了模拟计算,结合实验结果讨论了蓝宝石晶体热性能的各向异性对晶体生长的影响.研究结果表明,对于冷心放肩微量提拉蓝宝石晶体生长系统,较大的轴向热导率有利于提高晶体的生长速率和界面稳定性,而稍大的径向热导率则有利于保持微凸的生长界面.晶体内的热应力受径向热膨胀系数的影响显著,随着径向热膨胀系数的增大而增大,最大热应力总是出现在籽晶与新生晶体的界面区域.在实验中选α轴为结晶取向,成功生长出了直径达230mm、高质量蓝宝石晶体. 相似文献
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Mohammad Hossein Tavakoli Talaye Arjmand Abasi Shirin Omid Ebrahim Mohammadi‐Manesh 《Crystal Research and Technology》2013,48(2):58-68
In this paper, for an inductively heated Czochralski furnace used to grow sapphire single crystal, influence of the inner (wall‐to‐wall) and crystal internal (bulk) radiation on the characteristics of the growth process such as temperature and flow fields, structure of heat transfer and crystal‐melt interface has been studied numerically using the 2D quasi‐steady state finite element method. The obtained results of global analysis demonstrate a strong dependence of thermal field, heat transport structure and crystal‐melt interface on both types of radiative heat transfer within the growth furnace. 相似文献
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Kyropoulos (Ky) method is the most suitable technique for the growth of high‐quality sapphire single crystal for substrate applications. Cracks are often observed in the grown ingot that significantly reduces industrial productivity. In the paper, cracking causes are analyzed by examining crystal shape, thermal stress and three‐dimensional effects during the stable growth of sapphire crystal. It is found that locally induced thermal stress around the shoulder of the crystal is the largest. However, thermal stress is not fully responsible for the cracks, since the predicted stress level is lower than a critical value regarding crystal cracking. Polycrystalline growth or/and other crystal defects must be another factor that degrades the critical value and makes the crystal more fragile. Simulation results further show that crystal shape has less effect on the thermal stress level, although experiments have shown that crack‐free crystals usually have smooth surfaces. The initial cracking position in the ingot predicted in simulation agrees well with experimental observation after considering crystal defects in a qualitative discussion. From the view of three‐dimensional simulation, the variation of heating condition during growth may result in high thermal stress locally that leads to the cracks at one side of the crystal. Additionally, three‐dimensionally unexpected temperature drop of the heater may be responsible for the sticking‐to‐crucible phenomenon at the shoulder region of the grown crystal. 相似文献
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H. S. Fang J. Tian S. Wang Y. Long M. J. Zhang C. J. Zhao 《Crystal Research and Technology》2014,49(5):323-330
Crystal quality during Czochralski (Cz) growth is influenced significantly by the convexity of solid/liquid (S/L) interface, which is related to operating conditions, such as Radio‐Frequency (RF) coil position, crystal rotation and crucible rotation. Generally, a flat interface shape is preferred for high‐quality crystal growth. It is difficult to achieve the optimized conditions even from numerical modeling due to the large computational load from examining all of the affecting factors. Orthogonal design/test method, fortunately, provides an efficient way to organize the study of multiple factors with the minimization of computational load. In the paper, this method is adopted to investigate the affecting factors of Cz‐sapphire single crystal growth based on the coupled calculation of thermal field and melt flows. The orthogonal analysis clearly reveals the optimized growth conditions to achieve a relative flat S/L interface under the current ranges of the parameters. 相似文献
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光伏发电以绿色、可再生、能源质量高和不受资源分布地域的限制等优点被广泛使用,单晶硅又以低衰减率和高转换效率等优点渐渐超过了多晶硅光伏电池在市场中的份额,但成本问题和产能问题一直束缚着单晶硅太阳能产业的发展。本文提出了一种在晶体生长过程中随硅液面下降而下降的直拉单晶炉热屏结构,来解决在拉晶过程中坩埚上升所造成的拉晶速度和稳定性降低以及拉晶能耗增加的问题,并以CL120-97单晶炉热场为研究对象,利用有限元仿真对单晶炉优化前后晶体和熔体的热场以及氩气流场进行分析。分析仿真结果表明,优化后单晶炉不仅可以提高单晶炉拉晶的速度和质量,而且还能有效降低单晶炉拉晶的能耗。 相似文献