Mechanical characterization of fine grained silicon carbide consolidated using polymer pyrolysis and spark plasma sintering

In this study fine grained bulk silicon carbide ceramics are processed using a novel approach that involves pyrolysis of a preceramic polymer followed by spark plasma sintering (SPS). Allylhydridopolycarbosilane (AHPCS) is used as the preceramic polymer that is pyrolyzed under inert conditions to produce SiC powder. Fourier transform infrared spectroscopy (FTIR) is used to confirm complete conversion of the preceramic polymer to amorphous SiC at 1400 °C. Subsequently, spark plasma sintering (SPS) is used to compact the SiC powder at temperatures ranging from 1600 to 2100 °C at a uni-axial pressure of 70 MPa and a soak time of 10 min. In situ crystallization of amorphous SiC using SPS results in fine grained structure with grain size ranging from 97 to 540 nm. Close to theoretical density materials are obtained, at the higher sintering temperatures, with mechanical properties that exceed those of commercially processed sintered silicon carbide.