Carbon Fiber Composites Containing Strongly Coupled Si₃N₄ Nanowire-Carbon Nanotube Networks for Aerospace Engineering

Constructing strong interaction architecture is the key to achieve high mechanical performance because local interlaminar force can act as an efficient and robust bridge. Herein, closely interconnected network of Si3N4 nanowires and carbon nanotubes (SNs-CNTs) were designed and in situ introduced into carbon/carbon composites (CCs) for boosting their mechanical strength and friction performance, via a successive method of catalyst-assisted pyrolysis of polyureasilazane, isothermal chemical vapor deposition and chemical vapor infiltration. Fully covered SNs-CNTs allow increasing the bonding of fiber/matrix interfaces and the cohesion of pyrolytic carbon (PyC) matrix, leading to a better microcrystallinity of PyC in CCs. Owing to the synergistic effect of SNs and CNTs, the mechanical properties and friction properties of SNs-CNTs reinforced CCs exhibited obvious improvement. Compared with pure CCs, the interlaminar shear strength of SNs-CNTs reinforced CCs is increased by 59.87%, and the compression strength of SNs-CNTs reinforced CCs is increased by 32.69%. The friction coefficient of SNs-CNTs reinforced CCs is decreased by 39.50%, and the wear rate of SNs-CNTs reinforced CCs is decreased by 69.88%. Enhanced mechanical properties could be ascribed to the strong interaction between Si3N4 nanowires and carbon nanotubes. The present work highlights the importance of designing the three-dimensional network structure for enhancing the mechanical and friction properties of CCs. SNs-CNTs reinforced CCs with excellent mechanical and friction properties are potential materials for aerospace engineering.