Crystallization behavior and microstructure of barium borosilicate glass–ceramics

Abstract

The crystallization mechanism and activation energy of glass–ceramics belonging to SiO2–B2O3–BaO–Na2O–CaO–TiO2–ZrO2–Nd2O3 system were investigated by Kissinger and Ozawa methods using differential thermal analysis (DTA) with different heating rates and particle sizes. The effect of different thermal treatment temperatures on the crystalline phases, microstructure of barium borosilicate glass–ceramics was also studied. The results show that two exothermal effects shift towards higher temperatures with increasing heating rate. In addition, the exothermal effects in the temperature range of 900–1050°C shift towards higher temperatures with increasing particle size. The activation energy E (Kissinger method) and Avrami constant n associated with zirconolite are 124.38kJ/mol and 3.4, respectively, indicating three-dimensional crystallization mechanism. The activation energy E (Kissinger method) and Avrami constant n associated with titanite are 166.13kJ/mol and 2.2, respectively, indicating two-dimensional crystallization mechanism. Only strip-shaped zirconolite crystals are observed in the bulk of the glass–ceramics when the thermal treatment temperatures are 750–850°C. Brick-shaped titanite crystals appear in the bulk of the glass–ceramics when the thermal treatment temperatures are higher than 900°C.