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.