ZrB2-SiC Composites Toughened by Interlocking Microstructure and Chopped Carbon Fiber

ZrB2-SiC ceramics present better oxidation resistance and mechanical properties than monolithic ZrB2 ceramics. However, the small damage tolerance and poor crack growth resistance, which result in the low fracture toughness, limit the engineering application of ZrB2-SiC ceramics. Focusing on this issue, microstructure design and introduction of toughening phase are two effective approaches to improve the fracture toughness of ZrB2-SiC ceramics. In this work, ZrB2-SiC and Cf/ZrB2-SiC composites were toughened respectively by interlocking microstructure and chopped carbon fibers via reactive hot pressing. For the ZrB2-SiC composites, the interlocking microstructure formed by in-situ ZrB2 platelets presented excellent self-enhancing effect. The ZrB2-SiC composites had high bending strength and fracture toughness. However, the composite exhibited typical brittle fracture characteristics. Compared with ZrB2-SiC composite, the flexural strength of Cf/ZrB2-SiC composite decreased, but the fracture toughness was comp