Smart Corrosion Inhibition Strategies – Substrate, Coating, and Inhibitors

By Thomas P. Schuman

Corrosion is a persistent problem for machinery and vehicles constructed out of metals, in particular those comprised of steel or aluminum alloys. The design of metal structures, as to the material and how it interfaces with the environment, plays a large role in the tendency to corrode since corrosion is a surface reaction. Surface composition and morphology, therefore, greatly affect the ability of metal to remain passive or to become corrosively active.

Materials design should dictate what surface compositions or morphologies are desired, and supplement the mechanical architecture, to maximize corrosion resistance. For active metal alloys, the cur­rently utilized bulk alloy specifications do not appear sufficient for ensuring a particular corro­sion activity. Surface conversion of the metal to either a less active or an actively corrosion-pre­venting coating may or may not passivate the resulting surface.

The application of a coating to a reactive metal surface is commonly utilized to retard or prevent corrosion of the surface, which can provide either passive or smart inhibition of corrosion processes. Smart systems at­tempt to utilize environmental or behavioral triggers to induce a response in the coating or sub­strate that changes surface composition to better inhibit corrosion. Design of active coating sys­tems and their mechanisms are reviewed.