Preparation of porous silicon nitride ceramics by coated pore-forming agent method

Coated pore-forming agent method was introduced to the modification of the ordinary pore-forming method to prepare porous silicon nitride ceramics with high strength and uniform distribution. The porosity and flexural strength of the ceramics were measured. SEM and optical magnifier were used to investigate the morphology and microstructure of the prepared ceramics. Results show that the flexural strength of these porous silicon nitride ceramics is much higher than that of those without coating process treatment. When the porosity is 50%, the flexural strength is increased by almost 100%. The enhancement of strength is ascribed to the uniform distribution of spherical pores and the partition of these pores.