Computational Modeling of Active Corrosion Inhibitor Release from an Al-Co-Ce Metallic Coating

An alloy coating has been developed for an AA2024-T3 substrate that can serve as barrier, sacrificial anode, and reservoir to supply soluble inhibitor ions to protect any defect sites. In this paper, the chemical throwing power of such an metallic coating under thin electrolyte films representative of atmospheric conditions is modeled. The geometry is that of an surface with the presence of a scratch simulating exposed AA2024-T3. The model calculates the time necessary to accumulate and inhibitors over the scratch when released from the coating under different conditions. The model factors in the pH-dependent passive dissolution rate of an alloy to define the inhibitor release flux. Transport by both electromigration and diffusion are considered together. The effects of scratch size, initial pH, chloride concentration, and electrochemical kinetics of the material involved were studied. Sufficient accumulation of the released inhibitor (i.e., the concentration surpassed the critical inhibitor concentration over AA2024-T3 scratches) was achieved within a few hours (e.g., for scratches of ) when the initial solution pH was 6 and the coating was adjacent to the AA2024-T3.