Using Electrochemical Impedance Spectroscopy as a Tool for Organic Coating Solute Saturation Monitoring

Branko N. Popov, University of South Carolina - Columbia
Mohammed A. Alwohaibi, University of South Carolina - Columbia
Ralph E. White, University of South Carolina - Columbia

© The Electrochemical Society, Inc. 1993. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in the Journal of the Electrochemical Society.

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DOI: 10.1149/1.2056233


Electrochemical impedance spectroscopy (EIS) has been used to study the solute uptake for epoxy/phenolic (E/p) and epoxy/amine (E/a) thick-coated mild steel samples immersed for 160 days in 3.5 weight percent NaCl solution exposed to air. Samples with thicknesses of approximately 200 µm with an exposed surface area of 22.6 cm2 were used to follow solute saturation of the organic coating. Good agreement was obtained between the calculated and measured coating capacitance when, according to the diffusion equation, the coating capacitance was plotted against exposure time.