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

• Novel reactive spark plasma sintering was used to densification ZrB2-ZrSi2-SiC composites.
• ZrSi2 and SiC reinforcements were synthesized by an in-situ reaction of ZrC and Si additives.
• Remarkable homogeneous microstructure and excellent mechanical properties

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·m1/2 and 471 ± 15 MPa, respectively, with the ZrSi2 + SiC content of 30 wt%.