热处理制度对Li_2O-Al_2O_3-SiO_2系统玻璃析晶及热膨胀系数的影响

Effects of heat-treatment on the crystallization and thermal expansion coefficient of Li_2O-Al_2O_3-SiO_2 system glass

采用传统熔融冷却法获得了以P2 O5 为成核剂的Li2 O Al2 O3 SiO2 系统基础玻璃 ,通过差热分析确定了使该玻璃微晶化的热处理条件 ,并获得了不同热处理温度下Li2 O Al2 O3 SiO2 系统低膨胀微晶玻璃 ;利用X射线衍射分析和扫描电子显微镜对晶化试样的物相和微观结构进行了研究 ;讨论了热处理制度对玻璃的析晶及热膨胀系数的影响 .研究结果表明 :以P2 O5 为成核剂 ,采用不同热处理制度能获得Li2 O Al2 O3 SiO2 系统低膨胀微晶玻璃 ;在析晶初始温度下进行热处理 ,析出 β 石英晶体 ,但晶体生长缓慢 ,结晶程度低 ;提高晶化温度 ,析出 β 锂霞石和 β 锂辉石晶体且晶体生长迅速 .

Basic glasses of Li_2O-Al_2O_3-SiO_2 system with P_2O_5 as nucleation agent were prepared by means of conventional melt quenching technology, and the heat-treatment conditions were determined by using DTA. The glass-ceramics with very low thermal expansion coefficient were obtained at different heat-treatment temperatures. The crystalline pha- ses, the microstructure of the glass-ceramics and the influence of heat-treatment on the structure and the thermal properties of the glass-ceramics were investigated according to the X-ray diffraction analysis and the SEM. The results show that the basic glasses in the Li_2O-Al_2O_3-SiO_2 system may be prepared at lower melt temperature and the low expansion glass-ceramics of Li_2O-Al_2O_3-SiO_2 system can also be obtained at different heat-treatment temperatures. The main crystal phase is β-quartz but this crystal grows slowly at the initial crystallization temperature, while β-eucryptite and β-spodumene grow rapidly at higher heat treatment temperature.