Effect of cordierite crystallization on the water absorption and pyroplastic deformation of an alumina-strengthened porcelain that contains fine talc

Abstract

The effect of cordierite crystallization on the densification and pyroplastic deformation (PD) of alumina-strengthened porcelain that contains talc is examined herein. During firing at a relatively low temperature below 1200 °C, the addition of fine talc powder with a mean diameter of approximately 7 µm is more effective in promoting the liquid phase sintering of the porcelain through an increase in the amount of the low-viscosity liquid phase due to Mg²⁺ doping than the addition of a coarse talc powder with a mean diameter of approximately 14 µm. Beyond the firing temperature, cordierite crystallization that is accelerated by the fine talc addition suppresses the PD of the porcelain through a decrease in the amount and an increase in the viscosity of the liquid phase due to the transfer of Mg²⁺ from the liquid to the cordierite crystals. As a result, a decrease in the water absorption (<0.5%) and PD index (<1.5 × 10⁻⁶ mm⁻¹) is realized for the porcelain with 32 mass % addition of the fine talc powder over a relatively wide firing temperature range from 1194 to 1336 °C.