Structure, chemical durability and microhardness of glass-ceramics containing apatite and leucite crystals

Glass-ceramics based on SiO2–Al2O3–K2O–Na2O–CaO–P2O5 prepared by controlled crystallization of glass are studied. Glass melted from a batch of high purity raw materials was quenched and milled. The powder was heat treated at 850°C, 900°C and 1150°C for 1 h, quenched in water, milled, formed and sintered at 1000°C for 1 min. The study focused on the phases of crystallization and microstructure of both heat treated and sintered samples. Microhardness and chemical durability were measured of glass-ceramics produced by sintering. Leucite and needle-shaped fluorapatite crystals were developed. The microstructure changed depending on heat-treatment and sintering temperatures. The chemical durability and microhardness of glass-ceramics prepared for restorative dental applications are influenced by the properties of the bulk glass.