College of Transportation Engineering, Xiamen City University
Fujian YongchunShuangheng Aluminum Co.,Ltd.

在封闭的定向凝固过程中,监控和预测凝固进程和相变界面形态是业内的难点。文章采用解析法对太阳能级多晶硅定向凝固过程进行求解,获得一种高精度凝固进程数学模型,由易于测得的散热温度和凝固时间推算凝固高度、瞬时凝固速率和熔体温度分布;通过求解Poisson(泊松)方程,建立三维的相变界面模型,揭示了熔体侧壁热流密度q值是影响界面形态的关键因素,为凝固工艺过程控制提供定量分析依据。以Si3303工业硅为原料,采用YITIPV型真空铸锭炉进行大尺寸(0.90m伊0.90m伊0.35m)铸锭实验。对于几何对称的相变界面,凝固进程数学模型与实验曲线的最大偏差为4.43%;而对于不规则的相变界面,最大偏差为8.68%,根据实验结果修正了凝固进程模型。通过检测杂质含量、电阻率和少数载流子寿命等参数,并比较4种铸锭的典型相变界面形态,验证了三维相变界面模型的预测准确性和可靠性。该模型可以为多晶硅提纯、其他金属、非金属的精密铸造和晶体生长工艺控制提供参考。

It is difficult to control and predict the solidification process and the morphology ofphase transition interface in sealed directional solidification. The directional solidification(D-S)process model of solar -grade polysilicon is solved by analytic method, and a high precisionmathematical model of solidification process is obtained. The solidification height, instantaneoussolidification rate and melt temperature distribution can be calculated from the easily measuredheat dissipation temperature and solidification time. By solving the Poisson equation, aD modelof phase transition interface was established. It is revealed that the heat flow rate q value on theside wall of the melt is the key factor to influence the interface morphology, which providedquantitative analysis basis for solidification process control. The large size(m) ingot casting experiments were carried out using industrial silicon as raw material inYITIPV vacuum ingot furnace. For the geometrically symmetric phase transition interface, themaximum deviation between the mathematical model and the experimental curve is%; for theirregular phase transition interface, the maximum deviation is%, and the solidification processmodel is modified according to the experimental results. The prediction accuracy and reliability oftheD phase transition interface model were verified by detecting the parameters such as impuritycontent, resistivity and minority carrier lifetime, and comparing the typical phase transitioninterface morphologies of the four ingots.

厦门市自然科学基金项目(3502Z202374052)