Dual toughening mechanisms via PyC/BN interphases and SiC whiskers in CCf/SiC composites fabricated by NITE process

Chopped carbon fiber (CC f ) reinforced SiC ceramic matrix composites (CC f /SiC CMCs) hold potential as thermal structural materials. In this work, we investigated the impacts of dual protective interphases (pyrolytic carbon/boron nitride (PyC/BN)) deposited via chemical vapor deposition (CVD), along with the incorporation SiC whiskers (SiC w ) contents (20 wt%) on the structure and properties of as-fabricated CC f /SiC CMCs by NITE route. Structural and mechanical characteristics were explicated by the relevant advanced characterization tools. The introduction of PyC/BN dual protective interphase effectively preserved its integrity at elevated temperature and improved the toughness significantly via fiber pull-out and interfacial debonding mechanisms. Furthermore, incorporating 20 wt% SiC whiskers (SiCw) as secondary reinforcement yielded a synergistic toughening effect, promoting both the crack bridging and fiber pull-out behavior. This dual toughening mechanism led to a notable enhancement in mechanical performance, revealing an optimum bending strength of ∼356 ± 9.089 MPa, and toughness of ∼5.31 ± 0.194 MPa m 1/2 . Additionally, the inclusion of SiCw contributed to the creation of spatial network structure, potentially reducing the thermal expansion. The insights from this study advance the understanding of microstructural engineering in CC f /SiC composites, enabling future low-cost design and manufacturing of high-performance composites for extreme environments.