Porous Silicon Nitride Ceramics Prepared by Carbothermal Reduction Method

Porous silicon nitride ceramics with high porosity and uniform pore structure were prepared by carbothermal reduction reaction between low-cost silicon dioxide and activated carbon. The influence of SiO2 particle sizes on their microstructures was investigated. Microstructures and mechanical properties of porous silicon nitride ceramics were studied by XRD, SEM and three-point bending measurement. XRD analysis showed that onlyβ-Si3N4 phase, minor ofα-Si3N4 phase and glass phase Y8Si4N4O14 were detected. SEM analysis showed that porous silicon nitride ceramics obtained were composed of rod-likeβ-Si3N4 grains and uniform pores. Porous silicon nitride ceramics with different porosities and good mechanical properties were fabricated by changing SiO2 particle sizes.