Effect of particle size of powders ground by ball milling on densification of cordierite ceramics

Abstract

Mixtures of calcined kaolin, calcined talc and alumina were ground to submicron particle size by ball milling, and the effect of particle size of the ground mixtures on the densification behavior of a cordierite sintered body was studied. As the particle size of the ground mixtures became smaller, the raw material powders were mixed more uniformly and the formation temperature of α-cordierite became lower. Dense and pore-free sintered bodies were obtained by firing ground mixtures with particle size smaller than 0.39 μm at temperatures as low as 1200°C. Cordierite sintered bodies prepared from mixtures with particle size 0.39 μm or smaller by grinding natural raw materials had bending strengths ranging from 140-160 MPa, and these values were larger than that of cordierite glass-ceramics reported by Hayashi et al.1) The thermal expansion coefficients of dense, high-strength cordierite bodies increased, because anisotropic thermal expansion could not lower the amount of thermal expansion in the pore-free body.