Effects of SiC on the microstructures and mechanical properties of B4C–SiC–rGO composites prepared using spark plasma sintering

In this study, B4C–SiC–rGO composites with different SiC contents were prepared by spark plasma sintering at 1800 °C for 5 min under a uniaxial pressure of 50 MPa. The effects of SiC on the microstructures and mechanical properties of the B4C–SiC–rGO composites were investigated. The optimal values for flexural strength (545.25 ± 23 MPa) and fracture toughness (5.72 ± 0.13 MPa·m1/2) were obtained simultaneously when 15 wt.% SiC was added to 5 wt.%–GO reinforced B4C composites (BS15G5). It was found that SiC and rGO inhibited the grain growth of B4C and improved the mechanical properties of the B4C–SiC–rGO composites. The clear and narrow grain boundaries of rGO–B4C and rGO–SiC, as well as the semi-coherent B4C–SiC interface, indicated strong interface compatibility. The twin structures of SiC and B4C observed in the composites improved their fracture toughness. Crack deflection and crack bridging caused by the SiC grains as well as rGO bridging and rGO pull-out were observed on the crack propagation path.