Microstructure and mechanical properties of B4C ceramics by spark plasma sintering

B4C ceramics with the addition of (2.5 % (Ti3SiC2+Si) +2.5 % CeO2+5 % ZrO2) and (2.5 % (Ti3SiC2+Si) +2.5 % La2O3+5 % ZrO2) as sintering aid were fabricated by spark plasma sintering process at 1650 C by applying 80 MPa pressure. The second phases produced by chemical reaction and the mechanical properties of these two ceramics were analysed detailed. The as-sintered ceramics exhibited good comprehensive mechanical properties, including the flexural strength of 485.8 MPa and 493.4 MPa, the fracture toughness of 4.9 MPa⋅m0.5 and 5.4 MPa⋅m0.5 as well as the Vickers hardness of 34.2 GPa and 34.8 GPa, due to the reduction of grain sizes, the formation of second phases and the energy dissipation resulted from the intergranular fracture.