Effect of Carbon Source and Adding Ratio on the Microstructure and Properties of Solid-state Sintering Silicon Carbide

With 6wt% total carbon additive amount, the microstructure and properties of pressureless solid-state sintered SiC(SSiC) were studied with different carbon sources and carbon source adding ratio. It is found that SSiC ceramics with inorganic carbon(carbon black) as carbon source have finer SiC grains and lower density. As the carbon additive amount derived from organic carbon source(phenolic resin) increases, the grain size of SiC grains in SSiC ceramics increases, the distribution of carbon phase in the ceramics is more homogeneous, the density and the mechanical properties of SSiC ceramics increase. When the carbon additive amount derived from organic carbon source is3.0wt%, the ceramics with highest density have the largest elastic modulus, which is up to 486 GPa, the fracture toughness of it is 4.65 MPa·m1/2. When the carbon additive amount derived from organic carbon source is over 3.0wt%,the abnormal grain growth of SiC grains appears in the ceramics, the fracture strength and toughness further increase.At the same time, the thermal diffusion coefficient of SSiC ceramics with different carbon sources and adding ratio is also discussed.