Theoretical Efficiency of Metallic Dispersion Coatings for Corrosion Protection at the Cut-Edge

The theoretical efficiency of metallic dispersion coatings with release of corrosion inhibitor, e.g. zinc with dispersed inorganic particles capable of releasing corrosion inhibitor, is investigated by means of numerical modeling. The model is formulated for an Fe-Zn couple in a transient mode, including the formation of zinc corrosion products (ZnOH+, Zn(OH)2, Zn(OH)3 - and ZnO). Arbitrary Langrangian Eulerian (ALE) method is employed to allow displacement of the dissolving metal surfaces and link it with release of corrosion inhibitor from the zinc layer. With no inhibitor present, the model replicates the effect of self-healing at the cut-edge with respect to distribution of pH and zinc corrosion products. It has been found that release of small amounts of a corrosion inhibitor functioning on the principle of adsorption is already sufficient to enhance corrosion protection at the cut-edge. An additional contribution to self-healing at the cut-edge might be expected by enhanced precipitation of ZnO due to alterations in charge balance caused by introduction of negatively charged molecules of the inhibitor. © 2013, The Electrochemical Society, Inc. All rights reserved