Development of a Novel Flexible VOC-Free Chromate-Free Primer for Navy Aircraft

The military currently uses a flexible primer (TT-P-2760) as part of their coating system for many types of aircraft. This primer prevents film cracking and subsequent corrosion, especially at high flexing components and fastener patterns. However, itcontains organic solvents (VOCs) and chromate corrosion inhibitors that are now restricted for environmental reasons. Consequently, the Navy is seeking a replacement primer that meets or exceeds the existing primer specifications, but that does notcontain chromium or organic solvents. The novel coating system proposed here is comprised primarily of three low-cost, commercially available ingredients selected to provide low-temperature flexibility, excellent substrate and topcoat bonding, and therequired mechanical strength. The formulation also includes corrosion inhibitors and minor functional additives. Chromate inhibitors will be replaced by a package of inorganic and organic inhibitors that demonstrate comparable corrosion inhibition of Al2024-T3 and Al 7075-T6. Inhibitor leaching will be enabled by elevated pH conditions to provide