William F. Nelson
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Flash rusting is a corrosion process in which steel rapidly oxidizes upon contact with air at a high relative humidity. The ultimate goal of this research is to develop a bio-inspired flash rust inhibitor that is water-soluble and environmentally friendly. Several proteins and polypeptides from two classes of marine invertebrates have been identified for their potential to inhibit corrosion: the blue mussel Mytilus edulis and the sea squirts Mogula manhattensis and Styela clava. The most important feature of these biomolecules for corrosion prevention applications is the presence of post-translationally modified amino acid L-3, 4 dihydroxyphenylalanine (L-dopa). L-dopa has a well characterized ability to form strong bonds with metal ions, thus stabilizing the metal surface and inhibiting corrosion. Also, when enzymatically treated, L-dopa can participate in crosslinking reactions, which has been shown to lead to a thicker and more durable protein layer. In this study, cyclic potentiodynamic polarization was used to characterize the performance of the free amino acid form of L-dopa as a corrosion inhibitor. Mass loss and total charge passed were used to assess the extent of the corrosion reaction, and in addition, electrochemical impedance spectroscopy (EIS) data was also collected. The results indicated that L-dopa is ineffective as a corrosion inhibitor when not included as part of a larger polymer, most likely due to insufficient adhesion to the substrate. Preliminary exposure chamber tests were also done with an unpurified mixture of proteins from Mytilus edulis. The results indicate that the proteins are inhibiting corrosion effectively for a short amount of time before failing. To increase the effectiveness of the protein, different incubation conditions will be investigated in the future.
Douglas C. Hansen
Primary Advisor's Department
Materials Degradation and Electrochemical Engineering (Research Institute-Materials Engineering)
Stander Symposium project
"Controlling the Corrosion of Metals with Polyphenolic Proteins" (2012). Stander Symposium Projects. 125.