C0.3N0.7Ti-SiC Toughed Silicon Nitride Hybrids with Non-Oxide Additives Ti3SiC2

摘要

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