Structure, properties and toughening mechanisms of SiCw/SiC ceramics prepared by high-temperature and high-pressure sintering

In order to achieve dense SiC ceramics with better properties, SiC w /SiC ceramics without additives were prepared by high-temperature (1450 °C) and high-pressure (5.5 GPa) (HTHP) sintering using SiC whiskers (SiC w ) as a reinforcing phase. The high pressure causes the sintering temperature to be significantly reduced and the sintering time to be greatly shortened. A comprehensive analysis was conducted to elucidate the effect of SiC w content on the structure and mechanical properties of SiC ceramics. As the SiC w content increases, the properties of SiC w /SiC ceramics first improved and then decreased. At 5.0 wt% SiC w , there is the best bonding state between SiC whiskers and SiC matrix, therefore, SiC w /SiC ceramics exhibit the highest relative density of 99.08 %, maximum Vickers hardness of 23.02 GPa and fracture toughness of 9.02 MPa⋅m 1/2 . The main toughening mechanisms are assumed to be the crack deflection, bridging effect and pull-out of whisker.