This project demonstrated the capabilities of a self-repairing additive in a polyurethane topcoat (MIL-PRF-85285 Type II, Class H) applied to the exterior hangar doors in the severely corrosive environment at Corpus Christi Army Depot, Texas. Many conventional coatings when scratched or abraded, may develop corrosion that can lead to rapid deterioration of the substrate steel. The demonstrated self-repairing coating system was also applied to test panels exposed to atmospheric weathering and salt fog testing for 2,000 hours. While the self-repairing coating showed promise on the test panel exposure tests, the system was not able to protect the steel hangar doors due to the excessive mechanical impacts and stresses they are subjected to during daily operations. Department of Defense implementation of the demonstrated self-repairing coating is not currently recommended for use on infrastructure. Further evaluation would be needed to match the self-healing capabilities of the demonstrated coating with lighter-duty steel infrastructure components not subjected to the degree of impact and abrasion as the subject hangar doors. Because the self-repairing coating system did not perform any better than the conventional control coating in this project, the return on investment was zero.

This project demonstrated the capabilities of a vapor-phase corrosion inhibitor (VCI) as an additive into an epoxy primer coating for exterior hangar doors in a severely corrosive environment. Typically, protective coatings used on steel structures use zinc-loaded primers to provide corrosion protection to the substrate. As a more environmentally friendly option, a VCI-modified coating system has been used instead of a zinc-containing primer. The VCI migrates to the steel substrate to form a microscopically thin, corrosion-inhibiting film. The demonstrated coating system was also applied to test panels exposed to atmospheric weathering and to laboratory salt-fog exposure testing. The VCI-modified coatings were applied to abrasive-blasted substrates and to surfaces without the rust fully removed. Although the VCI-modified coating system showed promise in the test panel exposure results-especially panels with a lower grade of surface preparation-it was unable to protect the steel doors due to high levels of mechanical damage they incur during normal site operations. Based on the test panel results, further evaluation of the VCImodified coating system is considered necessary before making a positive recommendation for Army and DoD implementation. Due to the results of this demonstration, the project return on investment was zero.

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