Clay mixtures with petalite or β-eucryptite were studied with the aim of obtaining thermal shock resistant porcelain. β- eucryptite was synthesized by mixing Li2CO3 and Al(OH)3 with silica in stoichiometric compositions, and the synthesized β- eucryptite showed a thermal expansion coefficient of −7.10 × 10-6/oC. The final phase and coefficient of thermal expansion of the fired petalite-clay and eucryptite-clay samples were examined according to changes of the mixing ratio and firing temperature. In the petalite-clay samples, lithium alumina silicate (Li2O • Al2O3 • 7.5SiO2) and keatite-type β-spodumene, which shows a positive thermal expansion coefficient, were observed. In the eucryptite-clay samples, β-quartz-type β- spodumene was well developed according to the increase of eucryptite content and firing temperature. Under the conditions of 70 wt% eucryptite content and at a firing temperature of 1350 oC, the eucryptite-clay sample yielded a low thermal expansion coefficient of 0.7 × 10-6/oC. The mixing of β-eucryptite into clay enabled the realization of excellent thermal shock resistant porcelains.

Keywords: Thermal Expansion, β-eucryptite, Petalite, β-spodumene, Thermal shock resistance.