In situ synthesis mechanism and characterization of ZrB2–ZrC–SiC ultra high-temperature ceramics

The synthesis route, microstructure and properties of ZrB2–ZrC–SiC composites prepared from a mixture of Zr–B4C–Si powders by in situ reactive synthesis were investigated. The reactive path and synthesized mechanism of ZrB2–ZrC–SiC composite were studied through series of pressureless heat treatments ranging from 800 °C to 1700 °C in argon. The in situ ZrB2–ZrC–SiC composites were fabricated under different synthesis processing. The one with 88.4% relative density performed poorly in mechanical properties due to the occurring of self-propagating high-temperature synthesis (SHS). The fully dense ZrB2–ZrC–SiC composite was obtained under the optimized synthesis processing without SHS reactions. Its Vickers hardness, flexural strength and fracture toughness were 20.22 ± 0.56 GPa, 526 ± 9 MPa and 6.70 ± 0.20 MPa m1/2, respectively.