Toughening of SiC matrix with in-situ created TiB2 particles

SiC–TiB2 composites with up to 50 vol% TiB2 were fabricated by in-situ reaction between TiO2, B4C and C. The densification of the uniaxially pressed samples was done using pressureless sintering in the presence of sintering aids consisting of Al2O3 and Y2O3. The influence of the volume fraction of TiB2 and sintering temperature on density and fracture toughness was examined. It was found that fracture toughness is strongly affected by the volume fraction of TiB2. The presence of TiB2 particles suppresses the grain growth of SiC and facilitates different toughening mechanisms to operate which, in turn, increases fracture toughness of the composite. The highest value for fracture toughness of 5.7 MPa m1/2 was measured in samples with 30 vol% TiB2 sintered at 1940 °C.