Heat-resistant ceramics based on LAS-system non-metallic mineral and its thermal shock resistance

Abstract

Li2O-Al2O3-SiO2 (LAS) system-based ceramics have been prepared with petalite and kaolin and their thermal shock resistances investigated. Feed slurries in five combinations of petalite and kaolin composition between 40% and 60% were first prepared with 5, 15 and 35 μm fractions of petalite and slip casted into moulds. Then the casts were subjected to 2-stage sintering: in the first stage, at 850°C for 2 h and in the second stage, at 1200, 1250 and 1300°C for 2 h. Heating rate was 3°C per minute. The characteristics of sintering, microstructure, X-ray diffraction pattern and water absorption rate of the LAS ceramics produced were studied. Their thermal shock resistances were also measured by a directly flame contact method. Petalite was transformed into β-eucryptite and β-spodumene at temperatures higher than 1200°C. The LAS ceramics were found to have the highest thermal shock resistance at 1250°C. Even at the reduced addition of 45% petalite, the more the particle size of petalite increase, the better is thermal shock resistance of the LAS system ceramics. © 2010 The Ceramic Society of Japan.