Preparation and characterization of porous reaction bonded silicon nitride by paraffin emulsified suspension.

Porous Si 3 N 4 ceramics with an interconnected pore structure were prepared by a paraffin emulsified suspension method. The effects of the volume ratio of paraffin to silicon and Y 2 O 3 addition on the structure and properties of porous Si 3 N 4 were studied. Uniform dispersed pores introduced by the emulsified paraffine droplets can be observed in the green samples. With the increase of the volume ratio of paraffin to silicon, the bulk density and the strength of the sample were decreased, and the apparent porosity and Darcy permeability were increased. The formation of α-Si 3 N 4 whiskers could be promoted by the addition of the Y 2 O 3 during the nitriding process, and numerous nano whiskers could be obtained in the pores left by the paraffine droplets with suitable addition of the Y 2 O 3. The porous Si 3 N 4 with interconnected whiskers prepared via the paraffin emulsion method exhibited potential application for hot gas particular matter filtration. [ABSTRACT FROM AUTHOR]