Transparent MgO-Al2O3-SiO2 glass-ceramics prepared with ZrO2 and SnO2 as nucleating agents

Abstract

Transparent spinel glass-ceramics in MgO-Al2O3-SiO2 (MAS) system have been prepared by choosing tin dioxide and zirconia as nucleating agents. The effect of crystallization temperature on the crystallization properties, microstructure, and mechanical properties of the glass-ceramics were investigated. The results revealed that spinel, gahnite, and zirconia were observed in the glass-ceramics. The Kissinger method was used to calculate the crystallization kinetics of spinel glass-ceramics, and the crystallization activation energy was 381 kJ/mol. The grain size and content of the crystalline phase become higher with the rising crystallization temperature, and the transparency of glass-ceramics decreased. In terms of mechanical properties, raising the crystallization temperature induced higher microhardness and hence the bending strength first increased and then decreased. In the optimal preparation condition (810 °C/2 h + 1000 °C/2 h), the colorless and transparent glass-ceramics had excellent overall properties, with a microhardness of 9.3 GPa and bending strength of 170 MPa.