Portland State University. Department of Chemistry
Tami L. Clare
Date of Publication
Doctor of Philosophy (Ph.D.) in Chemistry
Colloids, Corrosion and anti-corrosives
1 online resource (xii, 69 pages)
The backbone of the industrialized world is comprised of refined, zerovalent metal, a material which thermodynamically favors an oxidative return to more chemically stable states. There are many methods used to slow or delay this process, such as protective coatings, sacrificial anodes, and alloys, but no method can entirely prevent corrosion. This body of work instead proposes detecting the earliest chemical markers of corrosion: that is, metal ions as they solubilize from a metal surface. Such information would allow maintenance personnel to make informed decisions about the necessity or lack thereof of preventive maintenance, and intervene before advanced damage has a chance to occur.
This dissertation finds that hydrogel-based sensors are capable of such detection and offer a multisensory response, with colorimetric, electrical, volumetric and vibrational changes. Both the colorimetric and electrical trends were calibrated and used for quantification of metal ions both in solution and directly from metal substrate surfaces. Observing how the hydrogels responded to various metal ions contributed to a greater understanding of how ion-headgroup associations can affect the sensory responses of a hydrogel, something that can be exploited in future sensor work. The ability of the sensors to detect ions directly from metal surfaces allowed for an investigation of the protective quality of fatty acids as corrosion inhibitors. A range of chain lengths were tested using the hydrogels, and the comparison to current characterization techniques showed good correlation. This accessible technique, beyond contributing to the current meager literature of fatty acids as corrosion inhibitors, can also allow for the determination of acceptable benchmarks of corrosion, information that is sorely needed to efficiently steward global infrastructure.
Price, Capri Ann, "Early Detection of Corrosion via Hydrogel-based Spectroelectrochemical Sensors" (2018). Dissertations and Theses. Paper 4637.
Video. Depicts the process of forming Prussian blue within the hydrogels. The concentrations shown are the ppm within the hydrogel
price-video2.avi (4042 kB)
Video. Depicts the process of removing the excess ferricyanide from the gels. Note that the 30 min soak is typically repeated with fresh electrolyte, not shown here for brevity. The concentrations shown are the concentration within the hydrogel