基于热力学模型的硅液中杂质组元活度研究

发布时间：2018-04-21 06:47

本文选题：Si熔体 + 分子相互作用体积模型　；参考：《昆明理工大学》2017年硕士论文

【摘要】：与传统能源相比,太阳能发电具有清洁节约、安全便捷、资源丰富等优点,是可再生的绿色环保能源。太阳能多晶硅(SOG-Si)是太阳光电转化的关键材料,具有制备工艺相对成熟、生产成本低及电池产品稳定等优点。目前,采用湿法冶金、合金精炼、真空精炼等方法提纯冶金级硅的冶金法由于建设周期短、生产能耗低、污染低等众多优点受到普遍关注。冶金法的各项工艺与硅熔体中各结构单元的热力学性质息息相关,但由于高温测定实验难度大造成相关工作严重不足。因此,通过模型模拟的方法获得Si基二元及多元体系的热力学性质将有很大的现实意义与指导价值。将获得的计算数据与文献报道值进行对比,验证了模型及方法的有效性与可靠性,为Si基熔体的热力学描述及冶金法提纯多晶硅奠定理论基础。本文采用MIVM模型计算了 Si-j(j=B、Mn、Ni)二元Si基熔体各组元的活度、无限稀活度系数等热力学性质,获得了 1700-1900K温度范围内,Si-j(j=B、Mn、Ni)二元Si基熔体中组元j的自相互作用系数等热力学数据。基于以上结果,进一步计算了三元Si基熔体:Si-Fe-j(j=Al、B、Mn)、Si-Al-Ni各组元的活度,获得了 1750-1900K温度范围内,Si-Al-Ni三元Si基熔体中A1与Ni的交相互作用系数与温度的表达式:εNiAl=-1.5136+5482.8088/T,以及1700-1900K温度范围内Si-Fe-Mn三元Si基熔体中Fe与Mn的交相互作用系数与温度的表达式:εMnFe=1.8825+2891.0303/T,并绘制了各体系的三元等活度相图。基于共存理论模型计算了 Si-j(j=P、Al、Fe、Ca)二元Si基熔体各结构单元的活度等热力学性质,获得了 1723-1873K温度范围内,Si-j(j=P、Al、Fe、Ca)二元Si基熔体中组元j的自相互作用系数等热力学数据。基于以上结果,计算了三元Si基熔体:Si-Fe-j(j=Ca、P)各结构单元的活度,获得了 1723-1873K温度范围内,Si-Fe-j(j=Ca、P)两个三元Si基熔体中组元Fe.与组元j(j=Ca、P)间的交相互作用系数与温度的关系表达式,并绘制了各体系的三元等活度相图。通过热力学推导发现,在1723K温度条件下,Si-Fe-Ca三元硅基熔体中杂质Ca(500-2500ppmw)的活度小于 CaSi 和 CaSi2 的活度,Fe(500-1500ppmw)的活度小于FeSi和FeSi2的活度,且CaSi2的活度大于CaSi,FeSi2的活度大于FeSi。
[Abstract]:Compared with traditional energy, solar power has the advantages of clean, economical, safe and convenient, rich in resources and so on. Solar polysilicon (SOG-Si) is a key material for solar photovoltaic conversion, which has the advantages of relatively mature preparation process, low production cost and stable battery products. At present, the metallurgical process of purifying metallurgical grade silicon by hydrometallurgy, alloy refining and vacuum refining has attracted widespread attention due to its advantages such as short construction period, low energy consumption and low pollution. The metallurgical process is closely related to the thermodynamic properties of the structural units in the silicon melt, but the related work is seriously deficient due to the difficulty of the high temperature measurement experiment. Therefore, it is of great practical significance and guiding value to obtain the thermodynamic properties of Si-based binary and multicomponent systems by the method of model simulation. By comparing the calculated data with the reported data, the validity and reliability of the model and method are verified, which lays a theoretical foundation for the thermodynamic description of Si based melt and the metallurgical purification of polysilicon. In this paper, the thermodynamic properties of component activity and infinite dilute activity coefficient of Si base melt are calculated by using MIVM model. The thermodynamic data such as the self-interaction coefficient of component j in binary Si based melt are obtained in the temperature range of 1700-1900 K. On the basis of the above results, the activity of Si-Fe-JJ element in Si-based ternary melt is further calculated, and the activity of Si-Al-Ni component in Si-Al-Ni alloy is calculated. The expressions of interaction coefficient and temperature between Al and Ni in Si-Al-Ni ternary Si-based melt at 1750-1900 K were obtained: 蔚 NiAl=-1.5136 5482.8088 / T, and the interaction coefficient and temperature of Fe and mn in Si-Fe-Mn ternary Si based melt at 1700-1900 K. The formula is 蔚 MnFe=1.8825 2891.0303 / T, and the ternary isoactivity diagram of each system is drawn. Based on the coexistence theory model, the thermodynamic properties of the structure units of Si-jjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjpjPnAlAlAlFeFeNCa-Ca2) binary Si based melt are calculated. The thermodynamic data such as the self-interaction coefficient of component j in the binary Si-based melt are obtained in the temperature range of 1723-1873K. Based on the above results, the activity of the structural units of the three-component Si based melt of 1: Si-Fe-Fe-jnjCa-CaP) has been calculated, and the component Fein in two ternary Si-based melts has been obtained in the temperature range of 1723-1873K. The relationship between the interaction coefficient and the temperature between the interaction coefficient and the component JJ JJ CaP) is expressed, and the ternary isoactivity phase diagrams of each system are plotted. It is found by thermodynamic derivation that the activity of impurity Ca500-2500ppmwin Si-Fe-Ca ternary silicon-based melt at 1723K is smaller than that of CaSi and CaSi2. The activity of CaSi2 is smaller than that of FeSi and FeSi2, and the activity of CaSi2 is larger than that of CaSiFeSi2.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN304.12

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