Effects of MO (M=Ba, Mg, Ca) on the crystallization of B2O3-Al2O3-SiO2 glass-ceramics

The effects of MO (M=Ba, Mg, Ca) on the crystallization of B2O3-Al2O3-SiO2 glass-ceramics were investigated by means of differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and dilatometer. MO can effectively facilitate the formation of B2O3-Al2O3-SiO2 glass which is influenced by the ratio of B2O3/SiO2, and the crystallization capacity of the glass turns to weaker with the decreasing of B2O3/SiO2 ratio. The main crystal phase is Al4B2O9 when the glass is heat-treated at 800 degrees C, and Al4B2O9 phase could transfer into Al18B4O33 with the heat-treated temperature increasing to 1100 degrees C. The calculation of crystallization activation energy (E) shows that crystallinity follows the order of CaO < MgO < BaO, and the Avrami parameter n is higher than 4, which indicate the crystallization of B2O3-Al2O3-SiO2 glass to be bulk nucleation with three-dimensional crystal growth. The addition of MO has evident effects on the main crystalline phase and the morphology of the crystals. (C) 2008 Elsevier Ltd and Techna Group S.r.l. All rights reserved.