Technical Approach

Researchers will conduct fundamental studies of the trivalent chrome process, a leading nonchromate conversion coating for which there is no understanding of if and how it provides active corrosion inhibition. Application of the techniques used to study chromates will be used to advance understanding of the inhibition mechanism of nonchromate inhibitors. As the design of coating systems relies on some combination of active inhibition, barrier properties, and adhesion, researchers will develop a better understanding of the tradeoffs. One major function of surface treatments is the improved adhesion of the primer layer, and researchers will study the adhesion and de-adhesion mechanisms. Researchers also will study inhibitor activation and transport in the primer layer. Inhibitive pigments in a polymeric paint matrix must be activated and transported to corroding sites, but again little fundamental understanding exists. Interactions and synergies between polymer matrix, pigment, surface treatment, and alloy are critical. Coating components largely have been developed independently but function as a system. Researchers will study these interactions and synergies. The local environments in coating systems also will be characterized. It is the coating/metal interfacial environment that controls the behavior of inhibiting species. The pH, oxidizing power, chemical aggressiveness (chlorine content), and temperature are the critical local environmental parameters that must be understood.