Coulostatic Perturbation Measurements and the Corresponding Time-to-Frequency Transform Data Analysis for Micro-Electrochemical Study

Abstract

Traditional micro-electrochemical impedance spectroscopy measurement using a capillary cell presents problems such as high ohmic resistance, long test duration and the subsequent possible tip blocking by corrosion products. In comparison, coulostatic perturbation measurements can avoid these issues due to its unique test principle and much shorter test duration. In this work, the coulostatic perturbation tests were performed on microregions of duplex stainless steel (DSS) 2205 immersed in 3.5 wt.% NaCl solution. The micro-electrochemical parameters were estimated by linear fitting the time-domain curve (LFTC), and subsequently by fitting the frequency-domain curve (FFC) obtained through Fast Fourier Transform (FFC-FFT) for comparison. It is shown that FFC-FFT method minimizes the problem of manual error in slope and intercept evaluation during LFTC. In comparison to the traditional EIS tests, FFC-FFT method causes less perturbation to the tested system, less interference of ohmic resistance with shorter test duration, thus can obtain valid low frequency data more efficiently, which is particularly favorable in studying high polarization resistance system or unstable systems. The micro-electrochemical experimental tests of DSS 2205 show that the polarization resistance of the microregion gradually increases with the increase of austenite phase, while the double-layer capacitance shows a decreasing trend.

Small-Area Techniques for Micro- and Nanoelectrochemical Characterization: A Review

“…Alternatively, a technique based on fitting the frequency-domain curve (FFC) obtained through a fast Fourier transform (FFT) is another way to study kinetic processes. 115 One more thing needs to be considered about the nonlinear relationship between the applied potential and the measured current, which means there is no guarantee that the current will respond to the applied sinusoidal potential. 44 Aside from corrosion research, the MCC technique has also been successfully applied to investigate other interesting aspects, such as electrodeposition of pure metal (e.g., Cu 116−118 and Ni 119,120 ), surface modification, 121 electrochemical machining, 122−125 electrocatalyst materials screening, 70,75,126−128 localized anodizing, 129,130 and thin-film properties characterization.…”

“…The most frequently used method is PDP, and smaller microcapillaries measure little EIS data due to its high ohmic resistance and long-term testing. Alternatively, a technique based on fitting the frequency-domain curve (FFC) obtained through a fast Fourier transform (FFT) is another way to study kinetic processes . One more thing needs to be considered about the nonlinear relationship between the applied potential and the measured current, which means there is no guarantee that the current will respond to the applied sinusoidal potential …”