Microstructure and mechanical properties of spark plasma sintered SiC-B4C gradient ceramics with Al additive

The SiC-B4C gradient ceramics were prepared by spark plasma sintering at 1800 degrees C under 40 MPa. The effects of Al content on microstructure and mechanical properties of the gradient ceramics were investigated. The results indicate that the microstructure and mechanical properties of the SiC-B4C gradient ceramics present gradient changes, and the addition of Al can significantly improve the mechanical properties. The microhardness and fracture toughness of each layer of the SiC-B4C gradient ceramics with 8 wt% Al additives were significantly improved, and the maximum values reached 26.20 GPa and 4.36 MPa m(1/2) , respectively. The densification kinetics for the spark plasma sintered SiC-B4C gradient ceramics and phase evolution in the sintering process were analyzed.