Effects of heat treatment temperature on crystallization and thermal expansion coefficient of Li2O-Al2O3-SiO2

The basic glass of Li2O-Al2O3-SiO2 system using P2O5 as nucleator was prepared by means of conventional melt quenching technology, and the heat-treatment process was determined by using differential thermal analysis. The crystalline phases and the microstructure of the glass-ceramics were investigated by using X-ray diffraction and scanning electron microscopy. The results show that the glass based on Li2O-Al2O3-SiO2 oxides using P2O5 as nucleator can be prepared at lower melt temperature of 1 450 degreesC and the glass-ceramics with lower thermal expansion coefficient of 21.6 X 10(-7) degreesC(-1) can also be obtained at 750 degreesC. The glass-ceramics contain a few crystal phases in which the main crystal phase is beta-quartz solid solution and the second crystal phase is beta-spodumene solid solution. When the heat treatment temperature is not higher than 650 degreesC, the transparent glass-ceramics containing beta-quartz solid solution can be prepared. beta-quartz solid solution changes into beta-spodumene solid solution at about 750 degreesC. And the appearance of the glass-ceramics changes from translucent, part opaque to complete opaque with increasing temperature.