Synchronously enhanced multifunctional properties of carbon fiber/phenolic composites by constructing SiCN@PyC-CNTs heterointerface

Carbon fiber/phenolic (CPE) composites have emerged as a kind of candidate material in the electromagnetic shielding field, owing to their lightweight, high strength, and excellent electrical conductivity. SiCN ceramic shell@pyrolytic carbon (PyC) is strategically incorporated into matrix, followed by in-situ growth of vertically aligned fibrous-like carbon nanotubes (CNTs) to construct a SiCN@PyC-CNTs heterogeneous interface at the fiber/matrix interphase, which enables precise modulation of the mechanical, tribological, electromagnetic interference (EMI) shielding, and thermal conduction properties of carbon fiber/phenolic composites. Specifically, the SiCN@PyC-CNTs heterostructure enhances interfacial polarization and forms conductive pathways under alternating electromagnetic fields. Compared with carbon fiber/phenolic composites, the tensile strength and elastic modulus of SiCN@PyC-CNTs reinforced composites (177.3 ± 12.62 MPa, 4.72 ± 0.06 GPa) exhibit remarkable improvements of 74.37 % and 14.56 %, respectively. The wear rate (1.28 × 10⁻¹³ ± 0.03 × 10⁻¹³ m³ N⁻¹ m⁻¹) is reduced by 37.56 %. Notably, the maximum EMI shielding effectiveness exceeds 70 dB in the X-band at a sample thickness of 0.4 mm, while the diffusion coefficient (0.348 ± 0.009 mm²/s) and thermal conductivity (0.582 ± 0.014 W/(m·K)) are enhanced by 12.62 % and 45.14 %, respectively. This study elucidates the synergistic effects of the SiCN ceramic shells and high-density CNTs on interfacial structural design, proposes a reinforcement mechanism based on heterogeneous interfaces, and demonstrates the promising application prospects of carbon fiber/phenolic composites in Low Earth Orbit/Medium Earth Orbit Probe Skin System.