We have developed a new coating to prevent the corrosion and cracking of marine grade aluminum. The key to this approach is a new class of corrosion inhibitors, developed using a combination of computational modeling and performance testing. These additives can prevent stress corrosion cracking (SCC) and intergranular corrosion (IGC) of sensitized 5XXX-series alloys. These additives are incorporated into an existing, commercially available marine-grade coating. This new chemistry uses active organic inhibitors that release slowly and continually from the coating, passivating the sensitized metal to prevent intergranular corrosion and SCC. This technology allows even sensitized aluminum alloys to perform similarly as new unsensitized aluminum. The coating also incorporates an advanced resin system and pigment package designed to reduce the coating’s surface temperature and weight. By lowering the surface temperature, the coating will delay if not completely prevent the sensitization of the metal. The corrosion resistance and other coating properties have been verified using in-lab tests, extended shoreside outdoor exposure testing, and shipboard testing. After 14 months of shipboard testing, the coating was still in excellent condition, and showed minimal to no signs of deterioration. The coating that includes the optimized corrosion inhibitor additives has been submitted for MIL-PRF-24635 approval.

Subject
Test methods, Coatings, U bends, Reflectance, Metals, Elongation, Corrosion inhibitors, Salt spray corrosion testing, Sensitization, Maritime, Corrosion protection, Stress corrosion cracking, Slow strain rate technique
Keywords:
Corrosion inhibitors, aluminum alloys, sensitization, stress corrosion cracking, marine environments, corrosion protective coatings
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2023
Association for Materials Protection and Performance (AMPP)
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