Microstructure, mechanical properties and thermal shock resistance of ZrB2-SiC-Cf composite with inhibited degradation of carbon fibers

ZrB2-SiC-Cf composite with carbon coated carbon fibers was successfully prepared by low temperature hot pressing. This composite showed an excellent thermal shock resistance compared with those composites fabricated by hot pressing and spark plasma sintering using as-received carbon fibers. Toughening mechanisms such as crack deflection, crack branching, fibers pull-out and fibers bridging were obviously detected in ZrB2-SiC-Cf owing to the inhibited degradation of carbon fibers and the relatively weak fiber/matrix interfacial bonding, leading to a non-brittle fracture mode of the composite. Moreover, the composite exhibited an excellent thermal shock resistance with a high critical thermal shock temperature difference of 773 °C which is about twice those of the reported ZrB2-based ultra-high temperature ceramics. This work provides valuable guidance in the preparation of ZrB2-based ultra-high temperature ceramics with a combination of excellent properties.