Sintering by Hot Isostatic Pressing (HIP) and Spark Plasma Sintering (SPS) of Silicon Carbide (SiC) nanoparticles synthesized by laser pyrolysis pilot scale

Pure or with sintering additives (Al2O3 + Y2O3) SiC nanoparticles (20 nm) synthesised by laser pyrolysis at pilot scale were first cold pressed under 1 GPa and then sintered by Hot Isostatic Pressing (HIP) and Spark Plasma Sintering (SPS). Pure SiC samples densified by HIP have a higher density (95%) than SPS ones (80%). With help of sintering additives, both HIP and SPS samples are near theoretical density. Smaller grain size were observed for HIP pellets (pure similar to 35 nm and with additives similar to 100 to 200 nm). Whereas SPS samples grain size were between 100 nm and 1 mu m. A primary mechanical properties study demonstrates a hardness (28 GPa) and a toughness (6.5 MPa m(1/2)) optimum when crystallite size is around 200 nm.