Fabrication of porous SiC ceramics having pores shaped with Si grain templates

SiC porous ceramics were prepared by heating mixtures of Si powder and carbon black at 900 °C for 24. h in Na vapor. The grains of the Si powder were not only the source of Si for SiC but also served as templates for the pores in the SiC porous ceramics. Angular-shaped pores with sizes of 2-10, 10-150 and 50-150 μm were formed by angular Si grains with sizes of ≤10, ≤50 and ≤150 μm, respectively. The porosity of the SiC porous ceramics was around 55-59%. Spherical pores were also formed when spherical Si grains were used. A bending strength of 14. MPa was measured for the SiC porous ceramics prepared with the Si grains (≤50 μm).