Crystallization heat treatment curves of barium disilicate glass / Curvas de tratamento térmico de cristalização de vidro de dissilicato de bário

Abstract

The transformation of glasses into glass-ceramics by heat treatment has been widely studied to increase the toughness of glasses. Barium disilicate is a material that can be toughened this way, greatly increasing its range of applications. To predict the fraction of crystals as a function of heat treatment time and temperature, it is necessary to draw the curves relating these three quantities. For this, data on the nucleation rate and growth rate of barium disilicate crystals were obtained from the literature and processed in order to obtain equations as a function of temperature. These equations were applied to the Johnson-Mehl-Avrami (JMA) equation and integrated in the intervals corresponding to the isothermal treatments, constant cooling from the melting temperature and constant heating from the glass transition temperature, thus obtaining the curves for these three types of heat treatment.