Synchronously constructing networked Si₃N₄ nanowires and interconnected graphene inside carbon fiber composites for enhancing mechanical, friction and anti-ablation properties

Carbon fiber (C_f) reinforced pyrolytic carbon (PyC) composites simultaneously possessing robust mechanical strength, excellent friction performances and outstanding anti-ablation properties are demanded for advanced aerospace applications. Efficient architecture design and optimization of composites are prominent yet remain high challenging for realizing the above requirements. Herein, binary reinforcements of networked silicon nitride nanowires (Si₃N₄nws) and interconnected graphene (GE) have been successfully constructed into C_f/PyC by precursor impregnation-pyrolysis and chemical vapor deposition. Notably, networked Si₃N₄nws are uniformly distributed among the carbon fibers, while interconnected GE is firmly rooted on the surface of both networked Si₃N₄nws and carbon fibers. In the networked Si₃N₄nws and interconnected GE reinforced C_f/PyC, networked Si₃N₄nws significantly boost the cohesion strength of PyC, while GE markedly improves the interface bonding of both Si₃N₄nws/PyC and fiber/PyC. Benefiting from the synergistic reinforcement effect of networked Si₃N₄nws and interconnected GE, the C_f/PyC have a prominent enhancement in mechanical (shear and compressive strengths increased by 119.9% and 52.84%, respectively) and friction (friction coefficient and wear rate reduced by 25.40% and 60.10%, respectively) as well as anti-ablation (mass ablation rate and linear ablation rate decreased by 71.25% and 63.01%, respectively). This present strategy for networked Si₃N₄nws and interconnected GE reinforced C_f/PyC provides a dominant route to produce mechanically robust, frictionally resisting and ablatively resistant materials for use in advanced aerospace applications.