1. Scope

Keywords

Rationale

Determination of corrosion rate is important for corrosion science and engineering. Many standards utilize techniques such as linear polarization resistance, electrochemical impedance spectroscopy, and electrochemical noise which are well-developed and acknowledged in research. All these standards are based on linear electrochemical techniques. With regards to non linear electrochemical phenomena and other methods to characterize the corrosion rate, potential perturbation signals with one or more sine waves at different frequencies have been applied. In the current guide, electrochemical harmonic measurement and its analysis are presented. A single frequency sine wave perturbation with defined amplitude is applied to a metal sample at open circuit potential. The resulting current response is recorded over time and then transformed to the frequency domain by Fast Fourier transform (FFT). The amplitudes of the first, second, and third harmonics of current are then obtained to compute the corrosion current and corrosion rate as well as the Tafel Slopes based on non linear electrochemical theory.