Electrically Conductive MXene-Coated Glass Fibers for Damage Monitoring in Fiber-Reinforced Composites

Multifunctional fiber-reinforced composites play a significant role in advanced aerospace and military applications due to their high strength and toughness resulting in superior damage tolerance. However, early detection of structural changes prior to visible damage is critical for extending the lifetime of the part. MXenes, an emerging class of two-dimensional (2D) nanomaterials, possess hydrophilic surfaces, high electrical conductivity and mechanical properties that can potentially be used to identify damage within fiber-reinforced composites. In this work, conductive Ti3C2Tx MXene flakes were successfully transferred onto insulating glass fibers via oxygen plasma treatment improving adhesion. Increasing plasma treatment power, time and coating layers lead to a decrease in electrical resistance of MXene-coated fibers. Optimized uniformity was achieved using an alternating coating approach with smaller flakes helping initiate and facilitate adhesion of larger flakes. Tensile testing with in-situ electrical resistance tracking showed resistances as low as 1.8 kΩ for small-large flake-coated fiber bundles before the break. Increased resistance was observed during testing, but due to good adhesion between the fiber and MXene, most connective pathways within fiber bundles remained intact until fiber bundles were completely separated. These results demonstrate a potential use of MXene-coated glass fibers in damage-sensing polymer-matrix composites.