Microstructure and Permeability Property of Si Bonded Porous SiC with Variations in the Carbon Content

The achievement of high gas permeability is a key factor in the development of porous SiC ceramics for applications of hot gas filter, vacuum chuck, and air spindle. However, few reports on the gas permeability of porous SiC ceramics can be found in the literature. In this paper, porous SiC ceramics were fabricated at temperatures ranging from 1600 o C to 1800 o C using the mixing powders of SiC, silicon, carbon and boron as starting materials. In some samples, expanded hollow microspheres as a pore former were used to make a cellular pore structure. It was possible to produce Si bonded SiC ceramics with porosities ranging from 42% to 55%. The maximum bending strength was 58 MPa for the carbon content of 0.2 wt% and sintering temperature of 1700 o C. The increase of air permeability was accelerated by addition of hollow microsphere as a pore former.