Demonstration of Galvanically Stimulated Release of a Corrosion Inhibitor

Abstract

Galvanic reduction of an oxidatively formed disulfide polymer of 2,5-dimercapto-1,3,4-thiadiazole (polyDMcT) in a conducting carbon paste releases its monomer anion in neutral NaCl. The monomer anion exhibits very good oxygen reduction reaction (ORR) inhibition at Cu cathodes. Coupling a carbon paste containing polyDMcT to a freshly polished metallic Al surface releases a corrosion inhibiting reduction product from the paste that can diffuse to and inhibit a remote cathode. This chemistry forms the basis for a "smart" corrosion inhibiting material that will release an ORR inhibitor when a corrosive environment couples the material to a base metal as would be the case for a coating with a defect. No release would occur in the absence of either the reducing force of the base metal, or the presence of a coupling ionic (corrosive) environment.