Distribution of Galvanic Corrosion

Abstract

The distribution of the galvanic corrosion of a nickel-to-steel couple in open, slowly moving, tap water was estimated from measurements of potential differences in the water around the couple. The distribution was confirmed later by thickness measurements. The two methods were in excellent agreement. The maximum galvanic corrosion of the steel occurred at the junction of the two metals and decreased as the distance from the junction increased. The maximum effect at the junction was 3~ times the average galvanic corrosion. The normal uncoupled corrosion of the steel was greater than the average increased corrosion due to the galvanic effect despite the three-to-one area ratio of nickel to steel. Potential measurements can be made as soon as a steady state is reached, but it usually takes considerable time for corrosion to become extensive enough for thickness measurements to be accurate.

Galvanic Corrosion Inhibitors for Cu/Ru Couple during Chemical Mechanical Polishing of Ru

“…8,9 Therefore, it is ideal if the galvanic corrosion current (i g ) could be measured. The general approach to estimate the i g of Cu is to measure the intersection of Cu anodic branch and Ru cathodic branch by conducting the electrochemical potentiodynamic polarization measurements, 5,10 as is schematically shown in Fig.…”

“…[5][6][7] However, practical corrosion process is influenced by many other factors such as the area ratio of anode/cathode, and the properties of the surface passive film. 8,9 Therefore, it is ideal if the galvanic corrosion current (i g ) could be measured. The general approach to estimate the i g of Cu is to measure the intersection of Cu anodic branch and Ru cathodic branch by conducting the electrochemical potentiodynamic polarization measurements, 5,10 as is schematically shown in Fig.…”

Review—On the Application of the Scanning Vibrating Electrode Technique (SVET) to Corrosion Research

“…94,96 Apart from numerical modeling, it should be mentioned at this point a set of papers published in the 1950s by Wagner 129 and Waber [130][131][132][133][134][135] who analyzed mathematically the current and potential distribution in solution for various types of electrochemical cells, sometimes using data from previous works. [22][23][24][25][26][27][28][29] Other papers worth mention are those of Nanis and Kesselman, 136 Miller and Belavance, 137 McCaferty, 138 and Morris and Smyrl. 139 The SVET operation and response has also been modeled in several works.…”

“…22,23 The concept was continued by several authors, notably Copson, Jaenicke, Akimov and Rosenfeld. [24][25][26][27][28][29][30][31][32] The book of Kaesche includes a chapter where most of these studies are analyzed. 33 In 1981, Isaacs and Vyas made a review of papers using this experimental approach and introduced the acronym SRET (Scanning Reference Electrode Technique) to designate the group of mapping techniques based on non-vibrating reference electrodes.…”

Concerns Continue Regarding Galvanic Coupling Article

“…Song wrote, “… there is no way that the rate of corrosion for a galvanic system will increase when dissimilar metals are separated by an inert spacer …” and that “… there must be an experimental error in measurement or some important factors overlooked… .” Verbrugge wrote, “… the analysis published by Boyd et al cannot be supported by any known and accepted corrosion theory or model …” and further stated that “Boyd et al reference my paper (Verbrugge, 2006) as though it lends support to their claims. This is not the case, nor would any earlier papers on this well‐studied topic [do so] (going back to, for example, Copson, 1943). ”…”