Nano-SiC / Carbon Nanotubes Composites : Elaboration and Thermomechanical Properties

B. Lanfant, Y. Leconte, G. Bonnefont, V. Garnier, Y. Jorand, G. Fantozzi, M. Pinault, M. Mayne-L’Hermite, N. Herlin-Boime
CEA, FR

Keywords: silicon carbide, carbon nanotubes, composite, spark plasma sintering, ceramics

Summary:

Nanostructured SiC matrix was reinforced by carbon nanotubes (CNT) dispersion in order to prepare composites for nuclear and aerospace applications. The aim was to overcome the brittleness of SiC ceramics while maintaining satisfying thermal conductivity. Therefore, CNT were expected to provide both mechanical reinforcement and thermal properties enhancement. SiC nanopowders smaller than 20 nm were synthesized by laser pyrolysis, and multiwall CNT were grown by catalytic CVD. These nanoobjects were dispersed and mixed in slurries, with or without sintering additives, in order to prepare green bodies to be densified by SPS. Nanometric SiC grain size was kept under 100 nm and CNT structure was also conserved upon sintering. Hardness, toughness and thermal conductivity values are presented here as a function of grain size and CNT content.