Electrochemical Impedance Spectroscopy (EIS) is a non-destructive technique that can be used to assess the corrosion behavior of materials. This study reanalyzed and discussed case studies on Microbiologically Influenced Corrosion (MIC) and Microbiologically Influenced Corrosion Inhibition (MICI) from recent literature to determine what fundamental information EIS analysis could or could not provide regarding the roles of biofilms and bacteria in corrosive and inhibitive processes.

The data were appropriately integrated and processed using Differential Impedance Analysis (DIA) to estimate the maximum number of time constants (T) constituting the equivalent electrical circuit (EEC) of each corrosion process considered. Further analysis on corrosion products by X-ray Photoelectron Spectroscopy (XPS) and EIS indicated that bacterial biofilm significantly influences the faradaic charge transfer and the resistance of the corrosive process film, as well as its inhibition at the metal-biofilm interface. It is noted, however, that the biofilm does not constitute an additional time constant.