硅灰石晶体在三元氧化物熔体中的生长行为研究

doi:10.15541/jim20150516

摘要/Abstract

摘要：

利用耦合FACTSage Toxide 热力学数据库的定量相场模型, 本研究模拟了硅灰石(CaSiO₃)在CaO-Al₂O₃-SiO₂体系中的恒温晶体生长过程, 并研究了熔体组分和温度对CaSiO₃结晶过程的影响。结果表明, 硅灰石的形貌主要由其表面能的各向异性所决定, 而几乎不受界面动力学的各向异性所影响。此外, 随着温度的降低, 析出的硅灰石的生长方式由平面生长向枝晶生长方式转变, 于此同时, 更加精细的枝晶结构也逐渐呈现出来。模拟所得的枝晶生长速度和尖端半径与Ivanstov理论所得结果一致, 和实验测得的数据也处于同一数量级。

关键词: 晶体生长, 形貌, 硅灰石, 相场

Abstract:

The process of isothermal wollastonite (CaSiO₃) crystallization in the CaO-Al₂O₃-SiO₂ system was simulated using a phase field model coupled with the FACTSage Toxide thermodynamic database. The effects of composition and temperature on the crystallization behaviour were studied. The simulations show that for the considered cases, the wollastonite morphology is mainly determined by anisotropy in the interface energy and hardly affected by anisotropy in the interface kinetics. In agreement with the observations from in-situ experiments, the simulations show a transition from planar to dendritic growth with decreasing temperature and the dendritic structure becomes finer when the temperature is decreased in further. The growth rates and dendrite tip radii obtained in the simulations agree well with Ivanstov’s theory and are of the same orders of magnitude as those measured experimentally.

Key words: crystal growth, morphology, CaSiO3, phase field

中图分类号:

TQ174

刘晶晶, HEULENS Jeroen, GUO Mu-Xing, MOELANS Nele. 硅灰石晶体在三元氧化物熔体中的生长行为研究[J]. 无机材料学报, 2016, 31(5): 547-554.

LIU Jing-Jing, HEULENS Jeroen, GUO Mu-Xing, MOELANS Nele. Isothermal Crystal Growth Behavior of CaSiO₃ in Ternary Oxide Melts[J]. Journal of Inorganic Materials, 2016, 31(5): 547-554.

图/表 6

Fig.1 Simulated morphologies of wollastonite at t=1 s for slag A at (a) 1320℃; (b) 1360℃ with anisotropy in the interface energy only (c) 1320℃ and (d) 1360℃ with anisotropy in interface energy and interface kinetics

Fig. 2 Simulated and experimental morphologies of wollastonite for different undercoolings for slag A: (a) ∆=65℃; (b) ∆=85℃; (c) ∆=105℃ after a simulation time of 1 s and (d) ∆=15℃; (e) ∆=35℃; (f) ∆=65℃ observed in the experiments

Fig. 3 Simulated and experimental morphologies of wollastonite for different undercoolings for slag B: (a) ∆=60℃; (b) ∆=80℃; (c) ∆=90℃ after a simulation time of 1 s and (d) ∆=0℃; (e) ∆=20℃; (f) ∆=40℃ observed in the experiments

Fig. 4 (a) The simulated dendrite in slag A at 1320℃ is presented by means of the 0.5 contour of ηliquid for different time steps, (b) dendrite tip position as a function of time. The dendrite tip velocity is determined as the slope of this line

Fig. 5 (a) Dendrite tip velocity and (b) radius of wollastonite dendrite as a function of the undercoolings. The data of phase field simulations (filled mark) are shown in comparison with experimental data (open mark)

Fig. 6 Products of dendrite tip velocity and radius as a function of the undercoolings. The data of phase field simulations are shown in comparison with experimental data and the solutions from the 2D and 3D Ivantsov relations. The ρv values obtained from the simulations for slag B overlap with those obtained from the 2D Ivanstov equation

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