Galvanic corrosion of Al/Cu meshes with carbon fibers and graphene and ITO-based nanocomposite coatings as alternative approaches for lightning strikes

Earlier airplane fuselages were made primarily of aluminum alloy sheets, which have very good electrical conductivity. If lightning strikes an aluminum alloy surface, the current generated by the lightning can easily flow without interruption or diversion to the interior of the aircraft. Today, fiber-reinforced polymer composites have been widely utilized in aircraft. In order to protect fiber-reinforced composites against lightning strikes, copper (Cu) and aluminum (Al) meshes or metal sheets are used in the uppermost layer. As it is known, carbon fibers are nobler than both Cu and Al meshes, resulting in galvanic corrosion when these dissimilar materials interact with each other under certain environmental conditions. Consequently, corroded metal mesh areas will lose conductivity on the composite surface. For this reason, lightning strike protection is vitally important for the new generation of composite aircraft. In the present study, we systematically studied the galvanic corrosion effects of carbon fibers and metal (Al and Cu) meshes in acidic and salty conditions. We found that environmental conditions had a big impact on the galvanic corrosion between carbon fibers and metal meshes used for fiber-reinforced composites. This paper discusses current lightning strike protection techniques and provides some experimental evidence of graphene and indium-doped tin oxide (ITO)-based nanocomposite coatings on carbon fiber-reinforced composites. This approach may overcome the problem of lightning strikes on composite aircraft and may be useful for redesigning the new generation of composite aircraft.