Communication—An Approach to Measuring Local Electrochemical Impedance for Monitoring Cathodic Disbondment of Coatings

Abstract

An electrochemically integrated multi-electrode array has been used for monitoring and visualizing the cathodic disbondment of defective coatings by measuring local electrochemical impedance. Compared with the conventional electrochemical impedance and local current measurement approaches, this new approach significantly enhances the sensitivity of detecting the propagation of coating disbondment by eliminating the effects of the dominating low impedance regions, such as those that arise at coating defects, and thus increases the visibility of higher impedance regions deep in the disbonded coating. Furthermore, it facilitates the probing of electrode processes and mechanisms in selected local electrode regions.

A critical overview of monitoring infrastructural health using corrosion probes

“…One recent progress in pipeline corrosion monitoring is the design of corrosion and coating degradation probes by innovatively applying the electrode array. The capability of the electrode array-based corrosion probes in detecting the initiation and propagation of localised corrosion and coating failure can be illustrated by several application cases [48][49][50][51]. Figure 3 illustrates a typical experimental configuration using an electrochemically integrated multi-electrode array-based probe to facilitate the in situ monitoring and visualisation of electrochemical processes occurring on buried steel surfaces under CP and anodic transient conditions [48].…”

“…2.44 mm x 2.44 mm) embedded in epoxy resin. Similar electrochemical cells and experimental set-up were used in various experiments for studying various inter-related processes such as cathodic shielding and localised corrosion [49,50], coating damage and disbondment [51]. More details on the experimental and data analysis methods can be found elsewhere [48][49][50][51].…”

“…New probe for monitoring of coating cathodic disbondment under overprotection [51,52] Cathodic disbondment is a major form of electrochemically induced coating failure that frequently takes place at the metal/coating interface on cathodically protected steel infrastructure such as pipelines. Extensive research over the past decades has developed a good understanding of the phenomenon; however, currently there is no technique that can be used to perform in situ monitoring of its occurrence in the that, under a CP potential of −1.40 V Ag/AgCl , the impedance of electrodes surrounding the defect area continuously decreased (to less than 10 5 ohm) over the 624 h exposure period.…”

“…Figure 6. Typical maps of impedance amplitude (│Z│ at 300 mHz) and direct currents measured over a coated probe after various periods of exposure and under different CP potentials[51].…”

In Situ Investigation of Under-Deposit Microbial Corrosion and its Inhibition Using a Multi-Electrode Array System

“…For instance, visualizing local electrochemical events on the metal surface in non-homogeneous surfaces, such as those created by biofilms and deposits ( Tan et al, 2011 ; Tan and Revie, 2012 ; Zhang et al, 2014 ). MEA systems have been used to study general and localized corrosion ( Sun and Yang, 2009 ; Tan, 1998 ; Tan, 2009 ; 2011 ), erosion-corrosion ( Xu and Tan, 2018 ; 2019 ), coating evaluation ( Varela et al, 2015 ; Mahdavi et al, 2016 ; Tan et al, 2017 ), UDC, and corrosion inhibition ( Muster et al, 2009 ; Turnbull et al, 2009 ; Hinds and Turnbull, 2010 ; Tan et al, 2011 ; Zhang et al, 2014 ) and most recently, to study MIC ( Dong et al, 2011 ; Liu et al, 2019 ).…”