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Chen C.,Hebei University of Technology | Chen H.-J.,Hebei University of Technology | Yu H.-Q.,Zhejiang Yunfeng New Energy Technology Co. | Yan W.-B.,Hebei University of Technology | And 3 more authors.
Rengong Jingti Xuebao/Journal of Synthetic Crystals | Year: 2013

In this article, the effect of different necking diameter on thermal field of sapphire crystal were simulated by CGSim software. The results indicate that the heat flux density decreased as the simulated and analyzed necking diameter decreasing, so were the axial and radial temperature gradients of crystal at the necking-shouldering stage. All of these can decrease the thermal stress, dislocation and low-angle grain boundaries and improved the quality of the crystal effectively. The actual products validated the simulation results of our experiments. Source


Liu W.,Hebei University of Technology | Lu J.,Hebei University of Technology | Chen H.,Hebei University of Technology | Yan W.,Hebei University of Technology | And 6 more authors.
Journal of Crystal Growth | Year: 2015

In this article, the influence of the flow field structure and temperature gradient of forefront interface on the shape of crystal-melt interface which may reflect the interface stability were analyzed through the method of numerical simulation by using CGSim software. In order to get a suitable interface shape and grow high-quality sapphire crystal, the heater arrangement should be adjusted during the KY process. The results indicate that the effect of Marangoni convection cannot be neglected at the last stage, the crystal-melt interface is governed by the flow field structure and the temperature gradient in melt at the crystal-melt interface. The phenomenon of shoulder concave appears at the stage of shoulder turning and interface inversion appears at the last stage during the crystal growth is discussed. Adjusting heater arrangement may effectively optimize the shape of crystal-melt interface. © 2015 Elsevier B.V. All rights reserved. Source


Chen C.,Hebei University of Technology | Chen H.J.,Hebei University of Technology | Yan W.B.,Hebei University of Technology | Min C.H.,Hebei University of Technology | And 4 more authors.
Journal of Crystal Growth | Year: 2014

In this work, a special crucible shape with a round shape for the outer wall and an inverted conical shape for the inner wall is presented to investigate the thermal and flow transport, as well as the shape of the crystal-melt interface during the Kyropoulos sapphire crystal growth, by using the numerical simulation method. The results show that the growth system with proposed crucible shape can result in more suitable thermal and flow fields, a lower convexity at shouldering and equal-diameter growth stage and a higher convexity at the following stage. Thus, the results are benefit for the quality of the sapphire crystal. © 2013 The Authors. Source


Yu H.-Q.,Zhejiang Yunfeng New Energy Technology Co. | Xu Y.-L.,Zhejiang Yunfeng New Energy Technology Co. | Shi H.-B.,Zhejiang Yunfeng New Energy Technology Co. | Liao Y.-J.,Zhejiang Yunfeng New Energy Technology Co. | Chen J.-M.,Zhejiang Yunfeng New Energy Technology Co.
Rengong Jingti Xuebao/Journal of Synthetic Crystals | Year: 2012

Using Kyropoulos method to grow sapphire crystal, often encountered the problem of adhesive crucible. Through the different experimental growth process, the adhesive crucible phenomenon about the shouldering, iso-diameter and tailing process was analyzed respectively. It pointed that the temperature field symmetry would be the main ways to eliminate the adhesive phenomenon. At the same time, it is suggested that at the end of the shouldering and tailing process one can increase the pulling velocity and increase the heat power. Source

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