EIS Equivalent Circuit Model: Electrolytic Damage Assessment of the Scribed Coated Steel Surface Embedded with Corrosion Inhibitor Capsules

Electrochemical Impedance (EIS) experimental data recorded on an intentionally inflicted scribe on Q-steel coated panels exposed in a laboratory environment was analyzed using equivalent electrical circu it-analog model technique for the corrosion-inhibition performance. The sand-blasted steel panels were pre-painted with a non-chromate industrial epoxy primer having dispersed corrosion-inhibitor capsules. A polyurethane topcoat layer was applied to the dried panel and the air-cured scribed panels were placed in contact with an ASTM D 5894 electro lyte. As oxidation kinetics init iate, embedded capsules leachates and oxides deposits are released into the scribe-area resulting in the addition of a sub-circuit component to the model for optimization-fitting of the experimental data. It is concluded that EIS modeling is a useful method and can be extended to study the corrosion-inhibition performance and the mode of corrosion react ion mechanism for the growth of iron oxide film on the scribe-area of a damaged coated film on the metal substrate.