Preparation and characterisation of low fusion leucite dental porcelain

Abstract Low fusion leucite containing dental porcelain was prepared from Egyptian feldspar and talc raw materials by firing for 6 min at 800-950° C. Porcelain frit was first made through fusion of the respective formulations at temperatures between 1100 and 1300° C and then poured into a cold stream of water. The frit was milled to pass a 75 μm sieve. Thermal expansion was followed using a dilatometer. The crystallisation of leucite was regulated by adjusting the rate of heating and by addition of nucleating agents. The main mineral phase developed is the tetragonal leucite form. The amount of crystallised leucite was monitored to control the translucency of the porcelain. Thermal expansion coefficient was in the range 10·0-14·5 × 10-6 K-1 (20-500° C). Microstructure was investigated using SEM.