Novel route to ?-SiAlON-SiO_2 ceramic composites

摘要

This paper reports a novel synthetic route to prepare dense ?-SiAION-SiO_2 ceramic composites. The stoichiometric ?-Si_4AI_2O_2N_6 extrudates prepared by the reaction sintering of a-Si_3N_4, á-AI_2O_3, AIN and Y_2O_3 precursor mixture at 1675°C for 4 h were fine ground, and mixed with different amounts of commercial fused silica (20, 40, 50, 60 and 80 wt-%) powder, dry pressed and sintered for 3-4 h at 1500-1750°C. These sintered materials were thoroughly characterised for bulk density, apparent porosity, water absorption capacity, phase composition, microstructure, hardness, dielectric constant and coefficient of thermal expansion. These characterisation results are presented and discussed in this paper.