Microstructure and mechanical properties of silicon carbide processed by Spark Plasma Sintering (SPS)

The unique combination of SiC properties opens the ways for a wide range of SiC-based industrial applications. Dense silicon carbide bodies (3.18±0.01 g/cm3) were obtained by an SPS treatment at 2050 °C for 10 min using a heating rate of 400 °C/min, under an applied pressure of 69 MPa. The microstructure consists of fine, equiaxed grains with an average grain size of 1.29±0.65 μm. TEM analysis showed the presence of nano-size particles at the grain boundaries and at the triple-junctions, formed mainly from the impurities present in the starting silicon carbide powder. The HRTEM examination revealed high angle and clean grain boundaries. The measured static mechanical properties (HV=32 GPa, E=440 GPa, σb=490 MPa and KC 6.8 MPa m0.5) and the Hugoniot Elastic Limit (HEL=18 GPa) are higher than those of hot-pressed silicon carbide samples.