Characterization and Crystallization Kinetics of a Diopside-Based Glass-Ceramic Developed from Glass Industry Raw Materials

Glass industry raw materials blended with 10 wt% technical grade TiO₂ powders were used to develop a glass-ceramic of the SiO₂-MgO-Al₂O₃-CaO-(Na₂O,K ₂O) system. On the basis of the DTA analysis, nucleation and crystallization experiments were carried out at 735 and 870°C, respectively. X-ray diffraction studies performed on the glass-ceramic system revealed the presence of the diopside as the major crystallizing phase comprising about 74 vol%. SEM investigations showed that the diopside crystals were formed as a result of surface nucleation and were conical in shape, between 15 and 40 μm in length and between 5 and 13 μm in width. DTA analyses were conducted at different heating rates and an activation energy for surface crystallization value of 150 kJ/mole was determined graphically from a Kissinger-type plot using the analysis of Matusita and Sakka. This value is about half of that for the same glass composition without the TiO₂ content.