Durable Hybrid Coatings Annual Performance Report (2009)

Abstract : The overall goal of this program is to contribute to the development of the next-generation anti-corrosion and other protective coating systems for USAF aircraft. During the past year, NDSU's promising Mg-based primer was further optimized. Five different Mg alloy pigments were evaluated, and the optimal pigment volume ratio was established. Flexible binders were identified that substantially improved mechanical properties of the Mg-based primer without sacrificing corrosion properties. Research continued to implement high-throughput methods for coatings formulation and optimization, including development of a technique that enables high-throughput screening of the abrasion resistance of cured coatings. A hybrid organic-inorganic binder for Mg-based primers was developed that includes silica nanoparticles, which has been shown to provide excellent corrosion resistance to important aluminum alloys. Research continued to develop a rapid-cure Mg-rich primer system that would minimize out-of-service time when an aircraft is repainted. These "dual-cure" binder systems combine ambient-cured siloxane networks with a UV-curable cross-linked network. Progress was made in developing in-field methods to deposit transparent conducting oxide coatings on aircraft canopies by atmospheric pressure plasma methods. Such coatings are needed to dissipate static charge buildup on canopies when in service. Finally, NDSU has investigated the use of electrochemical sensors embedded between the Mg-rich primer and the topcoat, to monitor the degree of corrosion protection provided by the primer. A principal advantage of this approach is that the topcoat protects the sensor from the environment, which reduces electrochemical noise, improves measurement accuracy, and extends the sensor lifetime.