Severe localized corrosion is often a result of microbiological factors such as the secretion of harmful metabolites, pH alterations, oxygen concentration differentials, and the formation of galvanic cells. Biofilm formation and corrosion kinetics are commonly evaluated through electrochemical methods utilizing both AC and DC current flows. This study combines macro- and micro-electrochemical techniques to provide an analysis of corrosion processes and to highlight the heterogeneity of microbiologically induced corrosion. Though traditional macro testing techniques can detect differences between biofilms formed by various microbes, this study utilized a microcapillary system in addition to the typical methodology as a mechanism to analyze localized phenomena. The overall response of the electrochemical processes across the surface was measured via macro-electrochemical methods, with the micro-electrochemical microcapillary technique used to distinguish local issues including active corrosion, passivity, and mixed behavior. The microcapillary system consisted of a 3D printed unit that was threaded into a microscope and interconnected the counter and reference electrodes to an interchangeable tip with a resolution of 20 μm. This resolution allows the microcapillary tip to produce a single-drop electrolyte which allowed for a precise, local measurement. The microcapillary testing identified both active and passive localized heterogeneities, demonstrating the limitations of solely relying on macro techniques. These results highlight the critical benefit of micro-electrochemical methods for detecting localized processes that are often unidentified by macro-scale analyses. This approach provides a more thorough understanding of microbiologically induced corrosion mechanisms and biofilm-induced variability and offers valuable insights for corrosion prediction and mitigation strategies.
