Synchronously constructing networked Si 3 N 4 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 (Si 3 N 4 nws) and interconnected graphene (GE) have been successfully constructed into C f /PyC by precursor impregnation-pyrolysis and chemical vapor deposition. Notably, networked Si 3 N 4 nws are uniformly distributed among the carbon fibers, while interconnected GE is firmly rooted on the surface of both networked Si 3 N 4 nws and carbon fibers. In the networked Si 3 N 4 nws and interconnected GE reinforced C f /PyC, networked Si 3 N 4 nws significantly boost the cohesion strength of PyC, while GE markedly improves the interface bonding of both Si 3 N 4 nws/PyC and fiber/PyC. Benefiting from the synergistic reinforcement effect of networked Si 3 N 4 nws 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 Si 3 N 4 nws 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.