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/cm(3)) were obtained by an SPS treatment at 2050 degrees C for 10 min using a heating rate of 400 degrees 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 mu m. 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 (H-V=32 GPa, E=440 GPa, sigma(b)=490 MPa and K-C 6.8 MPa m(0.5)) and the Hugoniot Elastic Limit (HEL=18 GPa) are higher than those of hot-pressed silicon carbide samples. (C) 2012 Published by Elsevier Ltd and Techna Group S.r.l.