Fabrication of Cordierite Ceramics by Densification/Crystallization of Glass Compacts and Evaluation of Their Thermal Shock Fracture Resistance

Abstract

Four kinds of cordierite ceramics were fabricated by firing the glass compacts having the composition of 2MgO⋅2Al₂O₃⋅5SiO₂ and the same composition with small amount of ZrO₂ at 1373K for 1h at heating rate of 6K/min and 20K/min. Their thermal shock fracture resistance was investigated through a rapid change in bending strength of quenched specimen. The critical quenching temperature difference (ΔT_c) of the sintered bodies with the chemical composition close to cordierite fired at 6K/min was about 650K, while the ΔT_c=550K for the sintered bodies fired at 20K/min. On the other hand, the cordierite ceramics with small amount of ZrO₂ revealed to have 500-550K as their ΔT_c. Although an addition of ZrO2 to cordierite composition and high heating rate have given rise to higher strength of sintered bodies, no effect on an increase in ΔT_c was recognized because Young's modulus and the thermal expansion coefficient of sintered bodies increased simultaneously.