Electrochemical investigations of organic, corrosion protective barrier coatings - limiting factors of small signal perturbation techniques

摘要

After a short introduction into the application of organic barrier coatings for corrosion protection the expectable parameters of the tested materials are discussed and the principle limitations are shown. Electrochemical impedance spectroscopy (EIS) is an already well known and also widely used technique, here only a very fundamental approach will be given. Relaxation voltammetry (RV) is a new electrochemical technology in the time domain. RV allows a two-step data interpretation: first a very direct and easy accessible extraction of the coating resistance and coating capacity from the raw data. Second, a much more detailed interpretation of electrochemical processes in the coating in terms of dielectric relaxation, diffusion and charge transfer is presented and discussed in this paper.