CNTi-SiC Toughed Silicon Nitride Hybrids with Non-Oxide Additives TiSiC.

In situ grown CNTi and SiC, which derived from non-oxide additives TiSiC, are proposed to densify silicon nitride (SiN) ceramics with enhanced mechanical performance via hot-press sintering. Remarkable increase of density from 79.20% to 95.48% could be achieved for SiN ceramics with 5 vol.% TiSiC when sintered at 1600 °C. As expected, higher sintering temperature 1700 °C could further promote densification of SiN ceramics filled with TiSiC. The capillarity of decomposed Si from TiSiC, and in situ reaction between nonstoichiometric TiC and SiN were believed to be responsible for densification of SiN ceramics. An obvious enhancement of flexural strength and fracture toughness for SiN with vol.% TiSiC ( = 1~20) ceramics was observed. The maximum flexural strength of 795 MPa for SiN composites with 5 vol.% TiSiC and maximum fracture toughness of 6.97 MPa·m for SiN composites with 20 vol.% TiSiC are achieved via hot-press sintering at 1700 °C. Pull out of elongated SiN grains, crack bridging, crack branching and crack deflection were demonstrated to dominate enhance fracture toughness of SiN composites.