Chromate-Free Flexible Coating

Todays chromated aircraft polysulfide primers provide excellent corrosion protection and a high degree of flexibility, which is required at seams and fasteners where there is large flexure. However, The Air Force would like to phase out these coatings because they have slow dry times, release high levels of VOCs and contain toxic hexavalent chromates. The MIL-PRF-32239A type 2 class 2 grade 1 specification requires a new primer with high elongation and corrosion protection, without using either a high VOC formula or chromates. TDA Research, Inc. has designed a new flexible resin to provide the needed balance of flexibility and chemical resistance in a fast drying, VOC compliant formula. Furthermore, in previous work, TDA developed a class of nonchrome corrosion inhibiting materials that can dramatically increase the corrosion protection performance through a targeted extended release mechanism. The Phase I feasibility study demonstrated that novel flexible coating has impact resistance better than the commercial flexible aerospace primers and excellent resistance to hydraulic fluid. In Phase II we will complete optimization of the coating. We will work with a major coating manufacturer to combine our chromate-free inhibitors with the novel flexible resin and formulate a flexible primer to meet MIL-PRF-32239.