Effects of TiC content on the microstructure and properties of B4C–TiB2–graphite composites by reactive hot pressing

Abstract

B4C–TiB2–graphite ceramic composites were fabricated via reactive hot pressing using B4C and TiC as the raw materials. With an increase in the TiC content, the grain size of B4C decreased continuously because B4C grain growth was inhibited by the TiB2 and C reaction products. However, excessive TiC content caused an increase in TiB2 and graphite grain size and the formation of TiB2–graphite agglomerates. When the composition of the ceramic composite was 95.1 wt%B4C–3.9 wt%TiB2–1.0 wt%graphite, the Vickers hardness and bending strength was optimized at 34.9 GPa and 688 MPa, respectively. The results showed that crack deflection is the main toughening mechanism of B4C–TiB2–graphite ceramic composites, and the effect of TiB2–graphite on crack propagation is particularly significant. When the composition of the ceramic composite was 75.6 wt%B4C–19.4 wt%TiB2–5.0 wt%graphite, the fracture toughness was optimized at 6.77 MPa·m1/2. These results provide guidelines on how to effectively control the combined properties of B4C–TiB2–graphite ceramic composites in future investigations.