Electrically Conductive Silver Nanoparticles-Filled Nanocomposite Materials as Surface Coatings of Composite Structures

Silver nanoparticles‐filled nanocomposite materials are fabricated and used as electrically conductive coatings for aerospace composite structures. Silver nanoparticles are first synthesized, then mixed with polymer solutions, and applied onto the surface of carbon fiber composite substrates either by casting or spraying technique. Two design strategies are studied: the reduction of nanofillers contact resistance using a conductive polymer as binder and the addition of a second polymer to fabricate a ternary biphasic nanocomposite for the further improvement of mechanical resistance of the coatings. The coatings are then annealed at different temperatures up to 200 °C and characterized using various techniques in order to evaluate their morphology, electrical resistivity, and mechanical performance. The thermal annealing considerably improves the adhesion of the coatings to the composite substrates as well as the scratch resistance of the coatings. A significant improvement (approx. six orders) of electrical properties is achieved for a ≈10 μm‐thick coating film after the thermal annealing. The best results are achieved with silver nanoparticles mixed with the conductive polymer binder with the maximum resistivity of 4.2 × 10−3 Ω g cm−2. The conductivity achieved here is fairly close to that values required in order for the materials to be used for coating of composite structures in potential aerospace applications such as electromagnetic interference shielding and lighting strike protection. Electrically conductive nanocomposite materials composed of silver nanoparticles (Figure a) mixed with a conductive polymer are fabricated and used as surface coatings for composite substrates. Thermal annealing at 200 °C considerably improves conductivity (Figure b) and mechanical properties (e.g., scratch test results in Figure c–d) of the coatings.