Fabrication of Porous Silicon Nitride with High Porosity by Carbothermal Reduction-reaction Bonding

By using cheaper Si, SiO2 and carbon black as starting material, the porous silicon nitride ceramics with high porosity and uniform pore structure were prepared by carbothermal reduction-reaction bonding method. The influences of Si content on the microstructure and mechanical properties of the samples were investigated. Micro- structures and mechanical properties of porous silicon nitride ceramics were studied by XRD, SEM and three-point bending measurement. XRD analysis showed that only β-Si3N4 phase, minor of -Si3N4 phase and glass phase Y3Si3O3N4 were detected in the samples. SEM analysis showed that porous silicon nitride ceramics obtained were composed of rod-like β-Si3N4 grains and uniform pores. Porous silicon nitride ceramics with different porosities and