Electrochemical Impedance Spectroscopy for Coating Evaluation using a Micro Sensor



Nicholas Waters Richard Connolly Douglas Brown Bernard Laskowski


This paper discusses a micro-linear polarization resistance (μLPR) sensor modified to perform coating evaluation by means of electrochemical impedance spectroscopy (EIS). A circuit model is used with the EIS data to measure solution resistance, pore resistance, charge transfer resistance, intact coating capacitance, and double layer capacitance. These measurements allow the end user to monitor degradation of protective coatings in real-time, through non-destructive means. This is demonstrated through an accelerated aging test using a coated metal plate with a modified μLPR sensor. A metal panel made from aluminum alloy 7075-T6 was coated with 2 mils of an epoxy-based polymer coating and 2 mils of high solids polyurethane. The sensor was adhered to the face of the coated panel in a manner that allowed the electrolyte solution consisting of 3.5% NaCl to flow between the sensor and the coated surface of the panel. EIS measurements were acquired every hour for a total of 35 hours and at the conclusion of the test, changes in key parameters within the circuit model identified the initial time and mechanism of coating degradation, in this case, delamination

How to Cite

Waters, N. ., Connolly, R. ., Brown, D. ., & Laskowski, B. . (2014). Electrochemical Impedance Spectroscopy for Coating Evaluation using a Micro Sensor. Annual Conference of the PHM Society, 6(1). https://doi.org/10.36001/phmconf.2014.v6i1.2340
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corrosion, structural health monitoring, Electrochemical Impedance Spectroscopy, EIS, Coating Evaluation, Paint

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