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,K2O) system. On the basis of the DTA analysis, nucleation and crystallization experiments were carried out at 735 and 870 degrees 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 mu m in length and between 5 and 13 mu m 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 TiO, content. (C) 1997 Elsevier Science Limited.