Strength and thermal shock resistance of alumina-strengthened porcelain containing cristobalite

The purpose of this study is to elucidate the effect of cristobalite on the strength and thermal properties of alumina-strengthened porcelain. The effects of milling time and sintering condition of mixtures on strength, density and thermal expansion properties were investigated by controlling the proportions of raw materials in compositions that generate cristobalite crystals upon heat treatment. At a composition of 15 mass% corundum, 8 mass% feldspar and 37 mass% fine-grained quartz powder, the highest bending strength of 230 MPa was attained with a bulk density of 2.6 × 10 3 kg.m -3 under appropriate milling conditions and with sintering above 1300°C. Although thermal expansion below 150°C was somewhat greater than that of general porcelain or alumina-strengthened porcelain, test bars of the porcelain resisted quenching with a temperature difference of 140°C, which assured its usability as porcelain for tableware.