Non-isothermal crystallization kinetics of some glass-ceramics with pyroxene structure

The kinetics of non-isothermal crystallization of two glass-ceramics obtained from a basalt rock, namely one without nucleating agents (BsM) and the other with the addition of 10% TiO2 and 2% ZrO2 (BsM1) was investigated using differential thermal analysis (DTA). The pyroxene structure of the two glass-ceramics was confirmed by X-ray diffraction (XRD). The activation energy as a function of the crystallized fraction was evaluated by Kissinger-Akahira-Sunose (KAS), Starink, Tang and Vyazovkin methods. The crystallization process of the sample BsM is accompanied by a single exothermic effect while the crystallization of sample BsM1 is accompanied by two exothermic effects on the DTA curve. The activation energies for sample BsM are very close to those associated to the Peak-1 of sample BsM1, varying between 325 and 345 kJ mol(-1) on the entire range of crystallized fraction, alpha. The activation energies associated to the Peak-2 of the sample BsM1 are about 100 kJ mol(-1) higher on the entire range of alpha compared with the activation energies of the sample BsM and those associated to the Peak-1 of sample BsM1. (C) 2012 Elsevier B.V. All rights reserved.