EFFECT OF CHANGING TIO2 CONTENT ON STRUCTURE AND CRYSTALLIZATION OF CAO-AL2O3-SIO2 SYSTEM GLASSES

This paper studied that the influence of changes in the TiO2 content o n the glass structure of CaO-Al2O3-SiO2 system and the formation of cr ystalline phases on reheating. The activation energy (E) for crystal g rowth and the Avrami parameter (n) have also been evaluated by means o f differential thermal analysis (DTA) techniques. The value of the Avr ami parameter (n) agrees well with scanning electron microscopy (SEM) observations of dendritic crystal growth from surface nuclei. In all t he CaO-Al2O3-SiO2 system glasses studied, dendritic crystals were obse rved. The greater the TiO2 content, the lower were the glass transitio n temperature, T-g, and crystallization peak temperature, T-p. The hig h value of T-p did not mean that value of E was large. The most effect ive addition of TiO2 was about 10.8% (by mass) in the CaO-Al2O3-SiO2 s ystem glasses. The difference of E between the base glass (no TiO2 add ed) and the glass containing most effective addition of TiO2 was very little. The experimental results suggest that in the studied samples, TiO2 cannot promote the crystallization very effectively. (C) 1998 Els evier Science Limited. All rights reserved.