Multifunctional nickel‐coated carbon fiber veil for improving both fracture toughness and electrical performance of carbon fiber/epoxy composite laminates

Abstract The poor lightning strike resistance limits the application of carbon fiber‐reinforced polymer (CFRP) composites in aircraft. Multifunctional fiber composites can reduce lightning strike damage by improving interlaminar mechanical properties and electrical conductivity. In this study, nickel‐coated carbon fiber (NiCF) veil was explored as a functional interleaf of CFRP composites to simultaneously improve the interlaminar fracture toughness ( G IC by 74.75% and G IIC by 36.22%) and through‐thickness electrical conductivity (by 220.49%). The toughening mechanisms of NiCF veils mainly include the pull‐out, debonding, and breakage of NiCFs, as well as peeling and splitting of nickel coating. The improvement of conductivity is mainly attributed to the increase of conductive paths. Furthermore, the NiCF veil‐interleaved laminates still maintained relatively high‐electrical conductivity after delamination, which was formulated as a structure–function relationship expression. The interesting finding is beneficial to lightning protection, especially for damaged composites. The NiCF veil is a potential interleaf for structure–function integration of composites, and has the potential to suppress lightning damage to aerostructures.