RELATIONSHIP BETWEEN HEAT-TREATMENT TEMPERATURE, CRYSTALLIZE PHASES AND THERMAL EXPANSION

Glass-ceramics were prepared from local raw materials in the Li2O–MgO–Al2O3–SiO2 system and its crystalline phases were characterized by differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and dilatometer (DIL). The effects of nucleating agents such as TiO2, Cr2O3, and P2O5 and heat treatment temperature (800oC, 900oC, 1000oC and 1100oC) on crystallization and morphology were also studied. The major phases formed were, LiAlSi2O6 and β-spodumene, in addition to enstatite and a little anorthite and hematite. With the exception of the high P2O5 containing glass-ceramic, the hexagonal