Silicon carbide coated carbon fiber made of conductive composite with health monitoring function

Recently, researchers at the Oak Ridge National Laboratory (ORNL) invented a roll-to-roll process that coats conductive carbon fibers with semiconductor silicon carbide nanoparticles, proving that such coated fiber materials are used as reinforcing materials for composite materials, Fiber-reinforced composites are more powerful and have new capabilities – their own structural health monitoring capabilities.

The carbon fiber composite material is composed of a polymer matrix such as an epoxy resin and a reinforced carbon fiber. Due to the different mechanical properties of the two materials, the fibers may be debonded from the substrate under excessive pressure or fatigue, which means that the damaged parts of the carbon fiber composite structure may be hidden under the surface and usually cannot be visually inspected. To, which can lead to catastrophic failure.

To make fibers embedded in nanoparticles, the researchers dipped high-performance carbon fibers into an epoxy resin loaded with nanoparticles with a particle size of 45-65 nm, and then placed the fibers in an oven to dry to cure the coating. When enough coated fibers are embedded in the polymer, the fibers form an electrical network that becomes a conductive composite. The semiconductor nanoparticles are capable of responding to the pressure exerted on the composite by a change in electrical conductivity, thereby adding an electromechanical function to the composite.

If the composite is deformed, the connectivity of the coated fibers will break and the electrical resistance in the material will change. If there is storm turbulence that causes the wings of such composites to bend, the electronic signal warns the computer wing on the aircraft that it has been under excessive pressure and prompts for an inspection.

ORNL's roll-to-roll technology demonstrates that this method can be used to produce coated fibers for next-generation composites on a large scale. This self-aware composite can be made from a renewable polymer matrix and a low cost carbon fiber material.