Influence of phosphorus pentoxide on crystallisation,microstructure and mechanical properties of potassium fluorophlogopite glass ceramics

Abstract

Potassium fluorophlogopite glass ceramics were prepared. Differential thermal analysis showed that there were two exothermic peaks at ～750 and 950°C, corresponding to the Avrami exponent ～1·5 and 2·0. Spherical particles were found using a scanning electron microscope when the glass ceramics were heat treated at 750 and 800°C. With the increase in heat treatment temperature, a kind of lamellar crystals was gradually formed, and the shape of crystals changed from spherical to lamellar when the Avrami exponent changed from 1·5 to 2·0. Mechanical tests showed that material cutting and bending strength increased, while the Vickers hardness decreased with the increasing of P₂O₅ content and heat treatment temperature.