In situ synthesis mechanism and characterization of ZrB 2–ZrC–SiC ultra high-temperature ceramics

Abstract

The synthesis route, microstructure and properties of ZrB 2–ZrC–SiC composites prepared from a mixture of Zr–B 4C–Si powders by in situ reactive synthesis were investigated. The reactive path and synthesized mechanism of ZrB 2–ZrC–SiC composite were studied through series of pressureless heat treatments ranging from 800 °C to 1700 °C in argon. The in situ ZrB 2–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 ZrB 2–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 m 1/2, respectively.