Fabrication and mechanical properties of porous Si3N4 ceramics prepared via SHS

Abstract

Abstract Porous silicon nitride ceramics were directly prepared by self-propagating high temperature synthesis (SHS). The effects of Si 3 N 4 diluent and Y 2 O 3 sintering additive on the phase composition and microstructure were investigated. The XRD patterns and SEM microstructures proved the sample with 63 wt% Si 3 N 4 diluent could provide appropriate temperature, reaction time and porosity for the fabrication of elongated β-Si 3 N 4 porous ceramics. A porosity of 40%–47% and a flexural strength of 118–216 MPa were obtained after SHS with different Y 2 O 3 content. Besides, the excellent thermal shock resistance of Si 3 N 4 assured that strength retention keeps stable in the temperature difference ( Δ T) of 800 °C.