Mapping Corrosion Kinetics Using the Wire Beam Electrode in Conjunction with Electrochemical Noise Resistance Measurements

Abstract

Conventional electrochemical methods have major limitations in measuring the kinetics of a heterogeneous electrochemical process such as localized corrosion. One reason for this is that traditional electrochemical kinetic methods are based on the fundamental Butler-Volmer equation 1,2 which only describes the kinetics of a uniform electrode process. Another reason is that traditional electrochemical techniques usually employ a one piece electrode which can only detect mixed or averaged electrochemical parameters over the whole electrode surface and cannot measure electrochemical parameters from a chosen location of the electrode surface. Although techniques such as the scanning reference electrode method and the scanning vibrating electrode method have been developed to detect localized electrochemical parameters in the solution phase, they do not delineate clearly the areas of cathodes and anodes 3 and they do not measure the kinetics of heterogeneous electrochemical processes.In order to measure local electrochemical parameters and to determine the kinetics of a heterogeneous electrochemical process, a wire beam electrode (WBE), 4-11 has been developed. Preliminary applications were in the study of the electrochemical heterogeneity of organic coatings 5,7,8,10 and localized corrosion processes. 4,6,[9][10][11] The WBE is normally fabricated from a bundle of electrically insulated drawn metal wires embedded in insulating material. However it could be prepared by techniques such as machining, casting, laser cutting, electric arc cutting, or electrodeposition. The surface of the WBE usually simulates the surface shape of a practical workpiece under study. Various previous designs and applications of the WBE can be found in Ref. 4-11. The WBE constitutes a unique integrated multielectrode system which effectively simulates a conventional one piece electrode surface. 4,6,10,11 Similar corrosion patterns were experimentally observed over a WBE and a large area one piece electrode surface when both electrodes were exposed to an identical environment. 4,10 The WBE differs from other sectioned electrodes such as the micromosaic platinum electrode, 12,13 the microcomposite glassy carbon electrode, 14,15 the platinum microelectrode array, 16 and other variously designed multielectrode systems 17-21 since these electrode systems, to our knowledge, were not integrated to simulate a heterogeneous electrode surface and were not designed to study heterogeneous electrochemical processes.The WBE is suitable for studying heterogeneous electrochemical processes. First, each wire in a WBE is an individual addressable electrochemical sensor which can measure local electrochemical parameters. Second, the surface area of each wire in an WBE is much smaller than the total working electrode area, thus electrochemical processes on each corroding wire surface can be assumed to be uniform even if the whole electrode surface is electrochemically nonuniform, an approach which is an analogy to calculus principles. 4 This assumption allows ele...

Monitoring pitting‐crevice corrosion using the WBE‐noise signatures method

“…This was achieved by summing up the corrosion depths over various periods of exposure to give a cumulative result [26]. Fig.…”

An overview of major methods for inspecting and monitoring external corrosion of on-shore transportation pipelines

“…[81][82][83][90][91][92] This design has the advantage of avoiding the electrochemical perturbation produced by shunt resistors and the ability of allowing the use of more sophisticated electrochemical techniques such as LPR 82 and electrochemical noise. 93 When used under CP conditions, the current densities measured by the WBE are almost completely cathodic obscuring corrosion rate evaluations by direct use of Faraday's Law. 7 Calculation method to obtain the anodic Tafel relationship of a system from its cathodic polarisation curve However, a new data analysis method has been recently developed to estimate corrosion rates and distributions based on the different current magnitudes measured by each electrode under CP.…”

Internal Current Effects on Localized Corrosion Rate Measurements Using Coupled Multielectrode Array Sensors

“…Later, other authors extensively used similar coupled multielectrode arrays to study the localized corrosion of different metals. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] The coupled multielectrode arrays are also called "wire beam electrodes" (or WBE) in the literature. [7][8] The coupled multielectrode arrays have been used as sensors (called coupled multielectrode array sensors or CMAS) for real-time monitoring of the rate of corrosion, particularly localized corrosion.…”