Cr2O3的添加对MgO-Al2O3-SiO2-TiO2系统微晶玻璃析晶行为的影响

利用DTA、XRD、SEM和TEM等实验手段,研究了Cr2O3的添加对于MgO-Al2O3-SiO2-TiO2系统微晶玻璃析晶行为的影响.同时,通过Ozawa和Kissinger方法计算出系统中α-堇青石的析晶活化能E.研究结果表明,少量Cr2O3的添加并不改变MgO-Al2O3-SiO2-TiO2系统玻璃析出的晶相类型,但是提高了玻璃转化温度Tg,降低了α-堇青石的析晶活化能.由于析晶活化能的降低,促进了α-堇青石的析出,最终获得了一种有实用价值的微波介质材料.该材料在微波频率下(10GHz)的相对介电常数约5.5,介电损耗＜7×10-4.

Effects of Cr2O3 Additive on Crystallization Behavior of MgO-Al2O3-SiO2-TiO2 Glass-ceramics

The crystallization behavior of MgO-Al₂O₃-SiO₂-TiO₂ glasses containing Cr₂O₃ was investigated by means of differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The crystallization activation energy (E) was also calculated by Ozawa and Kissinger methods. The results show that the initial precipitated phase and the main crystal phase are not changed by the Cr₂O₃ addition. Meanwhile, the glass transition temperature (T_g) increases and the crystallization apparent activation energy decreases. As a result the E values of cordierite is decreased, the formation of cordierite crystals is promoted. The glass-ceramic obtained by crystallization of the glass has dielectric constant around 5.5, and dielectric loss less than 7×10^-4.