R_2O-Al_2O_3-SiO_2系微晶玻璃析晶动力学研究

Crystallization Kinetics of R_2O-Al_2O_3-SiO_2 Glass-ceramics

通过对R2O-Al2O3-SiO2(R2O为Li2O,Na2O和K2O)系微晶玻璃DTA、XRD、SEM等测试分析,系统地对其析晶行为和析晶动力学进行了研究。该组分基础玻璃DTA曲线上有2个析晶放热峰,选取相应的热处理制度,可获得主晶相为Li2Si2O5和Li2SiO3的微晶玻璃。采用经典的计算方法对其析晶活化能(Ea)、析晶晶化指数(n)进行计算,结果表明:Li2Si2O5晶体和Li2SiO3晶体的析晶晶化指数n分别为1.70和0.87,均为表面析晶;由Kissinger方程计算出对应的析晶活化能为Ea1=151.4 kJ/mol、Ea2=623.1 kJ/mol。

The crystallization behavior and microstructure of R2O-Al2O3-SiO2 （R2O means Li2O, Na2O and K2O） glass-ceramic were investigated by means of differential thermal analysis （DTA）, X-ray diffraction （XRD） and scanning electron microscopy （SEM）. X-ray diffraction showed that the phases of glass-ceramics are Li2Si2O5 crystal and Li2SiO3 crystal corresponds to the two exothermic peaks on the DTA curves. The crystallization kinetic parameters including the crystallization apparent activation energy （Ea） and the Avrami parameter （n） were measured with Ozawa and Kissinger methods. The crystallization kinetic parameters of basis glass by Kissinger equation were calculated. The results show that： this basic glass is surface-crystallization. The basis glass which has two crystallization peaks corresponding to Eal = 151.4 kJ/mol, n （Li2Si205） = 1.70; E a = 623.1 kJ/mol, n （Li2SiO3） = 0.87; respectively.