Researchers at the Oak Ridge National Laboratory (ORNL) said that when the new polymer developed is used as a carbon fiber reinforced composite (CFRP) surface protective layer, it can be used as an effective protective layer for aircraft lightning protection.
CFRP is an ideal lightweight material and is often used for exterior parts of aviation aircraft. Although CFRP has obvious advantages in terms of weight reduction, it also has obvious disadvantages, namely poor conductivity and heat resistance, which makes the material more prone to lightning strikes. Therefore, the damage to CFRP caused by lightning strikes is often catastrophic.
Commonly used lightning strike protection (LSP) technology is to cover the top of the composite structure with metal foil or film. The outstanding disadvantages of this technology include weight gain, galvanic corrosion and expensive integration / maintenance costs. In ORNL's research, the researchers developed an easy-to-apply all-polymer lightning protection new material. The material is a thermosetting cross-linked polymer divinyl benzene (DVB) with polyaniline (PANI) and other intrinsically conductive polymers to make an adhesive layer with a thickness of 0.25-0.4 mm. In the experiment, the CFRP structure was coated with a PANI-based lightning protection layer. When the simulated lightning current was 100 kA, the sample achieved effective current dissipation, while the sample structure itself remained 100% safe. Because of its self-assembly performance, PANI has the ability to form a three-dimensional conductive network structure, which makes it more advantageous than carbon / metal nanofiller lightning protection technology. At the same time, the study also proved that the residual strength of the CFRP structure containing the PANI protective layer is close to 100%.
"We use 3D printing technology to coat the CFRP surface with an easy-to-operate adhesive material," ORNL's Vipin Kumar said. "The special polymer segment structure makes the material more conductive and stronger during heat treatment." In this study, the researchers conducted a controlled test to simulate lightning strikes on CFRP materials with and without polymer protection. "After visual inspection, the polymer-protected CFRP samples showed minimal damage and more uniform heat dissipation," Kumar said. "Experimental results show that the polymer layer provides an effective and continuous path for the lightning strike current."