ZrB2-ZrSi2-SiC composites prepared by reactive spark plasma sintering

ZrSi₂ and SiC are good candidates to improve both sinterability and mechanical properties of ZrB₂ ceramics, which were synthesized simultaneously by an in-situ reaction of ZrC and Si additives during the sintering processing in this work. The ZrB₂ ceramic composites with different amount of ZrSi₂ and SiC were fabricated by reactive spark plasma sintering (RSPS) method. X-ray diffraction, scanning microscopy and Archimedes's method are used to characterize the phase, microstructure and density of the composites. Meanwhile, fracture toughness and flexural strength of the obtained composites were investigated too. It's found that a fully dense composite can be achieved at 1500 °C by SPS. Both fracture toughness and flexural strength of ZrB₂ ceramics increased with increasing the concentration of ZrSi₂ and SiC additives and reached a maximum of 7.33 ± 0.24 MPa·m^1/2 and 471 ± 15 MPa, respectively, with the ZrSi₂ + SiC content of 30 wt%.