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Silicon nitride/silicon carbide nanocomposite materials: I, fabrication and mechanical properties at room temperature

: Herrmann, M.; Schubert, C.; Rendtel, A.; Hübner, H.


Journal of the American Ceramic Society 81 (1998), No.5, pp.1095-1108
ISSN: 0002-7820
Journal Article
Fraunhofer IKTS ()
Siliciumnitrid; Siliciumcarbid; Verbundwerkstoff; Pyrolyse

The fabrication of dense Si3N4/SiC nanocomposite materials that contained 2.5-30 wt% SiC via gas-pressure sintering and hot pressing was investigated. The SiC particles originated from admixed commercial SiC powders, SiCN powders produced by plasma synthesis, in situ reaction pyrolysis of carbon-coated Si3N4 particles, and pyrolysis of a polycarbosilazane-based SiCN precursor. Based on thermodynamic calculations, criteria for minimum liquid-phase decomposition during sintering were developed. The best sintering results were obtained for sintering cycles that observed this criteria. Materials that contained plasma-synthesized SiCN exhibited high strengths (835-995 MPa) and fracture toughness values (7.4-7.8 MPam1/2) at room temperature. Post-sintering thermal treatments led to a strength reduction.