High‐Strength Porous Silicon Carbide Ceramics by an Oxidation‐Bonding Technique

Abstract

Porous silicon carbide (SiC) ceramics were fabricated by an oxidation‐bonding process in which the powder compacts are heated in air so that SiC particles are bonded to each other by oxidation‐derived SiO 2 glass. Because of the crystallization of amorphous SiO 2 glass into cristobalite during sintering, the fracture strength of oxidation‐bonded SiC ceramics can be retained to a relatively high level at elevated temperatures. It has been shown that the mechanical strength is strongly affected by particle size. When 0.6 μm SiC powders were used, a high strength of 185 MPa was achieved at a porosity of ∼31%. Moreover, oxidation‐bonded SiC ceramics were observed to exhibit an excellent oxidation resistance.