Electrochemical Impedance Spectroscopy for Coating Evaluation using a Micro Sensor

Nicholas Waters, Richard Connolly, Douglas Brown, and Bernard Laskowski
Submission Type: 
Full Paper
Supporting Agencies (optional): 
Analatom, Inc.
phmc_14_077.pdf925.52 KBSeptember 17, 2014 - 12:48pm

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.

Publication Year: 
Publication Volume: 
Publication Control Number: 
Page Count: 
Submission Keywords: 
structural health monitoring
Coating Evaluation
Electrochemical Impedance Spectroscopy
Submission Topic Areas: 
Structural health monitoring
Submitted by: 

follow us

PHM Society on Facebook Follow PHM Society on Twitter PHM Society on LinkedIn PHM Society RSS News Feed