The phase transformation of R₂O-CaO-SiO₂-F glass-ceramics

Abstract

The phase transformation of R₂O-CaO-SiO₂-F system glass-ceramics with various additions of K₂O and F was investigated by DTA, XRD, SEM and other techniques. The crystallization and the microstructure of the obtained glass-ceramics were also evaluated. The phase separation occurred in CN1 specimen after being quenched in water, but phase separation did not appear in other quenched specimens with the content of K₂O and F increasing obviously, showing K₂O and F modified the structure of the glass-forming melts. The increase of K₂O and F resulted in the reduction of phase separation and the enhancement of crystallization. The main crystalline phase formed after heat-treatment was canasite and CaF₂. The microstructures of the crystalline specimens consisted of interlocking radial and granular crystals. Moreover, the crystallinity was increased as the content of K₂O was increased from 0.07 mol to 0.08 mol.

Keywords

glass-ceramics / canasite / phase transformation / crystallization

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