Mechanical property and gas filtration behavior of porous reaction bonded Si3N4 with monodispersed PMMA as pore former.

Porous Si3N4 ceramics were prepared by gel casting combined with a reaction bonding route using monodispersed PMMA as the pore former, and Isobam was used as a gel agent. With the PMMA addition varying from 0 to 20 wt.%, the bending strength was degraded from 94.0 to 39.1 MPa owing to the increased porosity and decreased bulk density. The β‐Si3N4 prismatic grains and round pores introduced by the monodispersed PMMA micro balls would endow the samples with high strength, and the permeability of the resulting samples was increased obviously with the increase of PMMA addition. Flue gas filtration test exhibited that the filtration efficiency of the porous ceramics filter was not degraded with introducing of the PMMA pore former, even though the permeability was increased obviously. The block type of the sample with 20‐wt.% PMMA additions during filtration was cake filtration, which indicates that the sample has the characteristic of being reusable after back‐blowing in flue gas filtration applications. Porous Si3N4 with high strength and permeability fabricated via the reaction bonding route exhibits great potential for low‐cost high‐performance ceramics filters. [ABSTRACT FROM AUTHOR]