Processing and microstructure of ZrB2–SiC composite prepared by reactive spark plasma sintering

In-situ formation of ZrB2–SiC composites was investigated by reactive spark plasma sintering of precursor powders according to the reaction B4C + 2ZrC + 3Si → 3SiC + 2ZrB2. The reaction and process presented here involves a diffusion reaction between B4C and ZrC which facilitates the formation of ZrB2, while liquid phase sintering of silicon facilitates atomic diffusion and combines with free C from the B4C and ZrC reaction to form SiC within minutes of heating and there were some residual unreacted precursor materials. An interpenetrating matrix of ZrB2–SiC was formed that shows increased fracture toughness (6.03 ± 0.45 MPa m1/2) despite relatively low density (95 %).