Hot press sintering of Li-phlogopite

Abstract

In the present work, the sintering and crystallization behavior of Li-mica glass-ceramic, prepared using pressureless and by pressure sintering method, were compared. Results showed that, by traditional method, first virgilite phase was formed at 760°C and then converted to Li-phlogopite (at 800°C), due to the fluoride evaporation, the Li-phlogopite phase (K0.86 Mg2.31 Li0.69 Al0.16 Si3.84 O10F2) decomposes at 1100°C and spodumene (LiAlSi2O6) with thermal expansion coefficient (CTE) of (4.64 × 10−6, °C−1) was produced. By using pressure sintering, virgilite phase was formed. It was stable in this system up to 1000°C. The specimen prepared by the latter method has no micro-cracks; its CTE was (7.53 × 10−6, °C−1).