UV-Initiated Healing of Punctures Due to Hypervelocity Impacts on Metal Composites for Space Applications

The space environment can have a severe impact on materials. In low Earth orbit (LEO) materials must withstand the effects of high vacuum, extreme temperature variations, micrometeoroid and orbital debris (MMOD), and exposure to atomic oxygen and UV radiation. Mechanical, chemical, and thermal degradation can occur due to exposure to a few or all these conditions. To help mitigate these damages, self-healing systems for the space environment are of interest. The objective of these systems is to autonomously repair damage without any external diagnosis, which can result in increased time/savings on repairs and the increased safety and reliability of materials. Our group is focused on designing metal composite self-healing pressure vessels for space that can heal hypervelocity impacts that occur due to MMOD. Many metallic self-healing systems require high temperatures for healing, which may not be effective in space due to the severe temperature variations. Our research group has designed a self-healing system that is more feasible for space. Instead of relying on heat, our system’s healing is UV-initiated, exploiting the UV radiation in space and it can be done in ambient temperatures. We designed a metal composite that sandwiches a liquid solution between two aluminum plates. The liquid is a precursor solution for a poly(ethylene glycol) diacrylate (PEGDA) hydrogel that cures via UV irradiation for less than 5 minutes. Upon puncture of the composite using a hypervelocity light gas gun to simulate space impacts, the precursor solution will be released and exposed to UV light, forming a hydrogel that will serve as a solid plug and heal the damage. In my presentation, I will discuss the design and characterization of the composite, along with a comparison of the mechanical properties before and after healing. I will also examine further testing methods that can analyze the efficiency of the system in space.