形核剂对Li2O-Al2O3-SiO2系微晶玻璃晶化过程的影响

采用差热分析(DTA),X射线衍射分析(XRD),扫描电镜(SEM)等分析手段研究了 TiO₂和TiO₂+ZrO₂两种形核剂对Li₂O-Al₂O₃-SiO₂(LAS)系微晶玻璃的形核和晶化的影响. 结果发现,样品经过不同温度的预形核处理后,采用TiO₂单一形核剂,晶化峰值温度和晶化峰 高度的变化较大,而采用TiO₂+ZrO₂复合形核剂,晶化峰值温度和晶化峰高度的变化较小. 当形核时间为2h,两种形核剂样品的最佳形核温度分别为745和760℃.晶化后均可得到纳米 结构的β-石英石固溶体晶相,其中采用TiO₂+ZrO₂复合形核剂样品的晶粒更细小.研究表 明采用复合形核剂的LAS微晶玻璃的形核过程对温度的敏感性小,有利于对形核过程进行控 制,同时形核效率高.

Effect of Nucleation Agent on the Crystallization of Li2O-Al2O3-SiO2 System Glass

The effect of 4wt%TiO₂ and 2wt%TiO₂+2wt%ZrO₂ on the nucleation and crystallization of Li₂O- Al₂O₃-SiO₂ system glass was investigated by the method of differential thermal analysis (DTA), the differential thermal analysis (DTA), X-ray diffraction (XRD) and the scanning electron microscopy (SEM). As the glass nucleates with a different thermal schedule, the crystallization peak temperatures all shift to lower temperatures. The changes of nucleation temperature and nucleation peak height of the glass added with single TiO₂ are larger than that of the glass added with TiO₂+ZrO₂. That means when TiO₂ is used as nucleation agent, crystallization is more sensitive as the variation of nucleation temperature than that of the glass added with TiO₂+ZrO₂. As all nucleation time is 2h, when TiO₂ is used as nucleation agent, the most effective nucleation temperature is 745℃, when TiO₂+ZrO₂ is used as nucleation agent, the most effective nucleation temperature is 760℃. When heat treated at most effective thermal schedule, the samples have grain sizes of 100～150nm for TiO₂ as nucleation agent, and of 50～80nm for TiO₂ +ZrO₂ as nucleation agent.