HfB2–SiC composite prepared by reactive spark plasma sintering

Dense HfB2–SiC composites were fabricated by reactive spark plasma sintering of a powder mixture composed of HfSi2, B4C and carbon. The relative density of the composites was 98.7% after reactive spark plasma sintering at 1600 °C under a pressure of 40 MPa for 10 min. Strong exothermic reaction occurred during the heating of the powder mixture due to the following reaction: 2HfSi2+B4C+3C=2HfB2+4SiC. The in situ formed HfB2 and SiC phases were homogeneously distributed. The average grain size of formed HfB2 and SiC was about 2 and 1 μm, respectively. The Vickers hardness and fracture toughness of HfB2–SiC composites were 20.4±1.5 GPa and 4.7±0.3 MPa m1/2, respectively. The present report proposes a method to densify HfB2-based composites at a low temperature.