Fabrication of porous silicon nitride with high porosity by diatomite

AbstractUsing low-cost diatomite and carbon black as raw materials, porous silicon nitride ceramics with high porosity and uniform pore structure was prepared by carbothermal reduction reaction. The influence of sintering additives 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 (-Si3N4 phase, minor of a-Si3N4 phase, Sialon phase Si5AlON7 and glass phase Y2Si3O3N4 were detected. SEM analysis showed that porous silicon nitride ceramics was composed of rod-like (-Si3N4 grains and uniform pores. Porous silicon nitride ceramics with different porosities and good mechanical properties were fabricated by changing the sintering additives