Microstructure and mechanical properties of ZrB2-based ceramic composites with nano-sized SiC particles synthesized by in-situ reaction

ZrB2 powders with nano-sized SiC synthesized by in-situ reaction were used to improve the sintering behavior and the mechanical properties of hot-pressed ZrB2-based ultra-high temperature ceramic composites. Microstructure analysis indicated that the mean size of ZrB2 and SiC particles was about 300 nm and 40 nm, respectively. The nano-sized SiC particles homogeneously distributed on the surfaces of ZrB2 particles. The introduction of nano-sized SiC via in-situ reaction significantly improved the densification process. In the ZrB2-based ceramic composites, the ZrB2 phase formed an inter-locking structure, which was beneficial to the improvement of mechanical properties. The dominant mechanisms for the improved mechanical properties are attributed to the plate-like ZrB2 grain pull-out, crack branching and crack deflection along the grain boundaries.