Microstructure and mechanical properties of TiB2-TiNw ceramic composite fabricated by SPS

A TiN whisker toughening TiB2 based ceramic composite was fabricated by spark plasma sintering (SPS). The influence of sintering temperature and holding time on the microstructure and mechanical properties of the composite was investigated. The results indicate that, at a sintering temperature of 1500°C and a holding time of 9 min, the composite exhibits a relative density of 99.24%, flexural strength of 906 MPa, fracture toughness of 8.6 MPa·m1/2, and Vickers hardness of 22.3 GPa. The sintering aid composed of Ni and Mo within the composite significantly enhanced atomic diffusivity in TiB2 grains, promoting a balanced grain growth rate. SPS technology promoted the rapid formation of numerous necks between TiB2 grains in a very short duration. Concurrently, the pinning effect exerted by TiN whiskers effectively inhibited excessively rapid migration of grain boundaries. These factors ensured that the composite could achieve optimized microstructures and good mechanical properties at a low sintering temperature.