含Bi_2O_3的MgO-Al_2O_3-SiO_2玻璃核化与晶化动力学研究

Study on Nucleation and Crystallization Kinetics of MgO-Al_2O_3-SiO_2 Glass Containing Bi_2O_3

使用差热分析(DTA)的方法研究了含Bi2O3的MgO-Al2O3-SiO2玻璃粉末(粒度≤0.054mm)的核化与晶化动力学。由此方法确定了样品最大成核速度温度,同时计算出晶体生长的活化能和动力学参数。结果表明,含Bi2O3玻璃的晶化指数(n)和晶体生长维数(m)都为1.15(约等于1),这说明该玻璃的晶化机制是表面晶化。由Kissinger和Augis-Bennett方程计算出的活化能较为接近,平均值为401kJ/mol。

The nucleation and crystallization kinetics of MgO-Al2O3-SiO2 system glass powder containing Bi2O3 with particle size ≤0.054mm were studied by differential thermal analysis(DTA).The temperature of maximum nucleation rate was determined from the DTA curves of samples heat-treated at different temperatures. The activation energy and kinetic parameters were simultaneously calculated from the DTA data using previously reported kinetic models. The crystallization process of a sample heat-treated at the temperature of maximum nucleation rate was fitted to kinetic equations with an Avrami constant,n=1.15 and a dimensionality of crystal growth,m=1.15,indicating that the crystallization behavior for the powdered glass containing Bi2O3 is governed by the surface crystallization mechanism. The values of an average activation energy calculated by the Kissinger and Augis-Bennett method is 401kJ mol-1.