Abstract
Micron-scale silver (Ag) wires were chemically oxidized in 0.05M FeCl3 solution to form Ag/AgCl reference electrodes. The wire electrodes were embedded between a topcoat and metal-rich primer-a sacrificial coating-to monitor the corrosion protection by its open circuit potential (OCP). A metal-rich system equipped with an embedded reference electrode (ERE) would allow in-situ measurement of the OCP; this indicates the level of protection afforded by the coating to the substrate and aims to eliminate the standard, less-accurate practice of scheduled maintenance. Measurement of the metal-rich primer/substrate OCP versus the ERE, and also versus a saturated calomel electrode (SCE), were the key experimental techniques to verify the concept's validity. Also, potentiodynamic experiments were utilized to mimic imposed-potential cathodic protection systems; the potential versus ERE, recorded with an additional potentiostat, responded favorably. This study shows the feasibility of a Ag/AgCl ERE for use in cathodic protective systems by effectively relaying OCP information. Further experiments using electrochemical impedance spectroscopy (EIS) and in-situ OCP measurements in a salt spray chamber strengthen this conclusion. This methodology allows the possibility of upgrading the monitoring and control systems currently used for imposed cathodic protection as well as the in-situ observation of corrosion protection levels for metal-rich sacrificial coatings.
Published Version
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