Novel route to β-SiAlON-SiO₂ ceramic composites

Abstract

This paper reports a novel synthetic route to prepare dense β-SiAlON-SiO₂ ceramic composites. The stoichiometric β-Si₄Al₂O₂N₆ extrudates prepared by the reaction sintering of α-Si₃N₄, α-Al₂O₃, AlN and Y₂O₃ 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.