NASA’s Langley Research Center has developed an innovative coating to heal cracks in metal components, such as in aircraft and bridges. Currently, the coating is used for in-laboratory repairs of surface cracks. Development continues with the ultimate goal of an in-situ healing mechanism that can work autonomously with structural health monitoring detectors.
A metal structure is coated with a low-temperature healing agent and when a crack is produced under cyclic load, it is then subjected to an external heat source (to heat the healing film to 250 °F – 300 °F). The component is processed in a vacuum. The coating has been prototyped on a titanium alloy sheet with an indium-tin eutectic alloy coating. Development is ongoing to produce a coating that does not require a vacuum and utilizes an integrated heat source.
The coating format works well with current aircraft practices. This technology has potential applications in aerospace and transportation infrastructure.