Effect of nucleating agents and heat treatments on the crystallization of magnesium aluminosilicate transparent glass-ceramics

Abstract

The crystallization behavior and transparent property of MgO-Al₂O₃-SiO₂ (MAS) glasses with TiO₂ and TiO₂+ZrO₂ as nucleating agents were discussed by differential thermal analysis, X-ray diffraction, field emission-environment scanning electron microscope, energy dispersive spectrum and UV-VIS-NIR scanning spectrophotometer. It was found that the glass crystallized at 950 °C with ZrO₂ less than 3% could obtain transparent glass ceramic, which presented purple to colorless. With the nucleating agent additives (5% TiO₂+3% ZrO₂), the colorless transparent glass-ceramics with spinel as the main crystal phase could be prepared, and the transmittance reached about 80%. As the crystallized temperature increase to 1 000 °C, besides spinel(MgAl₂O₄), sapphirine (Mg_3.5Al₉Si_1.5O₂₀) and ZrTiO₄ precipitated from matrix glass, and the transmitance of glass-ceramic decreased.

Keywords

nucleating agent / MAS glass-ceramic / transparent; spinel

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