The dependence of interlocking and laminated microstructure on toughness and hardness of β-SiC ceramics sintered at low temperature

Fully dense β-SiC ceramic has been sintered at low temperature (1500 °C) by spark plasma sintering (SPS) with Y4Al2O9 (YAM) and Y2O3 as additive. The sintered SiC samples have an interlocking and laminated microstructure of elongated grains, and reveal excellent mechanical properties. High hardness (31.2±1.54 GPa) and fracture toughness (6.6±0.37 MPa m1/2) are obtained simultaneously in SiC ceramics, which are quite different from previous researches. The indentation image shows that there are several different toughening mechanisms co-existing, which interact and further improve the fracture toughness of SiC ceramics.