Chromate-Free Fuel Tank Coating

The corrosion of military equipment is a significant and ongoing problem. Corrosion costs the Department of Defense $20 billion annually and is the number one cost driver in military life-cycle costs (U.S. Army Material Command 1997). To prevent this, metals are treated with protective coatings. These coatings must maintain their integrity and provide corrosion protection in the many different environments faced in each application. Aircraft fuel tank coatings must withstand: temperatures ranging from far below freezing (-65 °F) to above boiling (250 °F) without cracking, immersion in jet fuel without delamination and exposure to microbes that live at the water/fuel interface without undergoing microbial influenced corrosion. Long-term corrosion protection is particularly critical in integral fuel tanks because they are part of the aircraft structure and not easily repaired once in service. Current SAE AMS-C-27725 fuel tank coatings use high levels of soluble chromates to meet the corrosion performance requirements. Unfortunately, these hexavalent chromates are known carcinogens and their use and disposal is strictly regulated. An ideal integral aircraft fuel tank coating would be chromate-free and yet still provide the same corrosion protection as current chromated coatings. This SBIR project aims to develop a chromate-free, integral fuel tank primer using nanoparticle additives.