Journal of Inorganic Materials

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Effect of ZrO2 on Crystallization and Phase Transformation in Low-temperature Processed BaO-Al2O3-SiO2 Glass-ceramics

LU Yu-Feng, DU Yong-Guo, XIAO Jia-Yu, ZHANG Wei-Jun, WU Jian-Feng,YANG Guang, WANG Yue-Ran   

  1. (College of Aerospace and materials Engineering, National University of Defense Technology, Changsha 410073, China)
  • Received:2006-12-30 Revised:2007-02-04 Published:2008-01-20 Online:2008-01-20

Abstract: BaO-Al2O3-SiO2 (BAS) glass-ceramics with stoichiometric and off-stoichiometric celsian composition were fabricated, doped with B2O3 for melting and sintering. Crystallization and phase transformation characters of two groups of BAS glass-ceramics with and without ZrO2 were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and dilatometry. Results show that for both BAS glasses, the sintering temperature is lower than 850℃ and crystallization peak temperature is lower than 900℃. The crystallization characteristic of hexacelsian in each sample is bulk nucleation and three-dimensional growth because Avrami exponent is 2.8--3.9. The crystallization characteristic of monocelsian in the sample doped with ZrO2 is surface nucleation and one-dimensional growth because Avrami exponent is 0.95, while it is bulk nucleation and three-dimensional growth because Avrami exponent is about 3.0 in the sample without nucleation agent. It reveals that crystallization peak temperature and activation energy get lower in stoichiometric BAS glass-ceramics doped with ZrO2, while the crystallization peak temperature get higher in off-stoichiometric BAS glass-ceramics doped with ZrO2. Stoichiometric BAS glass-ceramics doped with ZrO2 crystallized at 850℃ for 12h is completely transformed into monocelsian. Monocelsian will not be detected in off-stoichiometric BAS doped with ZrO2 crystallized at 850℃ for 100h.

Key words: glass-ceramics, celsian, low temperature sintering, crystallization, phase transformation

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