Barrier Coatings with High Ohmic Resistance: Comparison between Relaxation Voltammetry and Electrochemical Impedance Spectroscopy

摘要

A new electrochemical method was established to measure the properties of barrier coatings. This technique is called relaxation voltammetry (RV) and is based on very sensitive current measurement and relatively high sample rates at the initial decay of the relaxation signal. The verification of the accuracy of this new method is done by measuring dummy cells with known resistors and capacitors. These results are compared with and confirmed by electrochemical impedance spectroscopy (EIS). The swelling and water uptake of two typical commercial organic coatings for corrosion protection are investigated and the RV and EIS data are discussed.