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 fiberreinforced 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.

Improving the through‐thickness electrical conductivity of carbon fiber reinforced polymer composites using interleaving conducting veils

“…The SEM images of both the veils are shown in Figure 1. Some nickel particles can be seen (highlighted with red arrows in Figure 1b) adhering to the fiber surface 40 . The random orientation of the veil fibers forms a uniform porous network structure, which aids in resin impregnation.…”

“…Recently Liu et al 40 reported that a nickel‐coated carbon fiber (NiCF) veil improves the electrical conductivity and fracture toughness of carbon fiber/epoxy composites. The unidirectional carbon fiber/epoxy prepregs were used for manufacturing the laminates.…”

“…Interleaves are also easy to add to the production process. However, the addition of interleaving materials reduces the fiber content and may have a negative impact on the mechanical properties of the laminates 40 …”

Simultaneously improve the mode II interlaminar fracture toughness, flexural properties, and impact strength of CFRP composites with short aramid fiber interlaminar toughening

“…[9][10][11][12] Among them, the interlaminar toughening technique is a targeted and straightforward method to improve the IFT of composites. Simply laying a layer of toughening materials, which can be materials such as particles, [13] veils, [14][15][16][17][18][19][20] films, [21] electrospun nanofibers, [22,23] and fibers, [24] and so forth, at a specific location (usually the middlemost layer) can be a good way to improve the IFT. Short fibers, being widely available and having excellent mechanical properties, are often used to improve the interlaminar fracture toughness of composites.…”

Thermal cycling of strained nickel‐coated glass‐epoxy composite laminates: Effects on macro mechanical and fiber‐matrix interface properties

“…[6][7][8] Nanoclays in conjunction with conductive fillers and nickel-coated fibers were used to increase the electrical conductivity of polymer composites. [9] Liu et al [10,11] incorporated nickel-coated carbon fiber veils in composite laminates, which improved the impact resistance and interlaminar fracture toughness (G IC , G IIC ), explained by additional energy dissipation through fiber pull-out breakage and peeling of the nickel coating. Ni-coated fiber composites have increased electromagnetic-wave absorptivity, which encourages their use in such applications as radar stealth, [12][13][14][15][16][17][18][19][20][21] interference shielding, [5] and microwave heating.…”