Cathodic reduction of oxygen on copper and brass

Balakrishnan, K.; Venkatesan, V.

doi:10.1016/0013-4686(79)80015-8

Cited by 40 publications

(19 citation statements)

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“…13 An influence on the reaction kinetics on pH as well as anion identity was also reported. 14 The study reported on herein is aimed at investigating the oxygen reduction reaction, taking place on a pure copper surface in naturally aerated 0.1 M Na 2 SO 4 solution as a function of pH. Separate ex- Figure 1.…”

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Diffusion-Limited Current Density of Oxygen Reduction on Copper

Vukmirovic¹,

Vasiljević²,

Dimitrov

et al. 2003

J. Electrochem. Soc.

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There are many important processes in corrosion for which the diffusion-limited current density of oxygen reduction, i L , plays a dominant role in terms of kinetic control. The conventionally accepted value of i L ͑for the four-electron reduction mechanism͒ which can be found in many corrosion textbooks is in the range of 50-100 A cm Ϫ2 , but the origins of this range of values are a bit mysterious. Previous research in our group aimed at ascertaining i L ͑under stagnant conditions͒ on a planar Cu electrode and a Cu microelectrode array in a naturally aerated 0.1 M Na 2 SO 4 electrolyte found that i L was in the range of 20-30 A cm Ϫ2 . In situ scanning tunneling microscopy was used to characterize the Cu surface at relevant potentials. Rotating disk electrode studies were used to measure i L in a naturally aerated 0.1 M Na 2 SO 4 electrolyte as a function of pH for both Pt and Cu electrodes. By comparing results for Pt and Cu we conclude that oxygen reduction occurs on a Cu surface via the four-electron mechanism. The oxygen diffusion-limited current density was found to be independent of pH ͑in the range 1.5-14͒. Finally, we conclude that our previous determination of i L in a stagnant electrolyte reflects an accurate range of values of the oxygen diffusion-limited current density.Oxygen reduction is important in corrosion because the kinetics of this process often determines general corrosion rates and damage evolution ͑e.g., pitting, crevice corrosion, stress corrosion, corrosion fatigue͒ in a number of commercially important alloys. Nevertheless, as briefly discussed below, there have been relatively few wellconceived experiments aimed at measuring the rate of oxygen reduction under conditions directly relevant to corrosion phenomena. To date, most of the significant work in this arena was aimed at studying the catalytic activity of Pt (hkl) to the oxygen reduction process using a rotating ring-disk electrode ͑RRDE͒ configuration under oxygen saturated conditions. 1 A significant motivation for the study that we report on herein is the key role of oxygen reduction in the corrosion of aluminum alloy 2024-T3. In this alloy, the corrosion rate is controlled by oxygen reduction on spatially separated microscopic intermetallic particulate phases that are highly enriched in copper owing to dealloying. 2-7 On immersion in a corrosive environment these intermetallic particles ͑e.g., S-phase Al 2 CuMg 2,4 ͒ support oxygen reduction, presumably according to the reaction 2H 2 O ϩ O 2 ϩ 4e Ϫ ϭ 4(OH) Ϫ , which results in a pH increase in the neighborhood of the local microcathodes. As the pH increases to about 9-9.5, 8-10 the passive oxide on the surface of the alloy matrix chemically dissolves causing the aluminum matrix to dissolve via the soluble AlO 2Ϫ anion. We note that the corrosion potential of Al alloy 2024-T3 in a 0.5 M chloride or sulfate electrolyte is Ϫ800 to Ϫ600 mV ͑saturated calomel electrode, SCE͒. 11 The general corrosion rate of the alloy and the subsequent extent of damage depend on kinetics of the o...

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confidence: 99%

Diffusion-Limited Current Density of Oxygen Reduction on Copper

Vukmirovic¹,

Vasiljević²,

Dimitrov

et al. 2003

J. Electrochem. Soc.

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“…The polarization curve in Figure 3 exhibits two plateaus (between −0.04 and −0.01 V versus SCE and above 0.005 V) and an abrupt increase in current in the vicinity of 0 V versus SCE. The response is a consequence of the chemical complexity due to the electrooxidation of the two principal alloying metals (copper and zinc), the influence of microalloying element (tin), and the cathodic reactions that take place: evolution of hydrogen and oxygen reduction [21][22][23]. Figure 4 shows the potential profile for the prototype, the simulation Beasy-GID, and the proposed simulation.…”

Section: Resultsmentioning

confidence: 99%

“…Formula (21) is used after getting and from (20), using the values of 1 and 2 given by (22) and (23). The final result is obtained iteratively using for this purpose Microsoft Excel.…”

Section: Resolutionmentioning

confidence: 99%

Corrosion Potential Profile Simulation in a Tube under Cathodic Protection

Ohanian¹,

Martínez-Luaces²

2014

International Journal of Corrosion

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The potential distribution in tubes of a heat exchanger is simulated when applying cathodic polarization to its extremes. The comparison of two methods to achieve this goal is presented: a numeric solution based on boundary elements carried out with the commercial software Beasy-GID and a semianalytical method developed by the authors. The mathematical model, the simplifications considered, and the problem solving are shown. Since both approaches use polarization curves as a boundary condition, experimental polarization curves (voltage versus current density) were determined in the laboratory under flow conditions and cylindrical cell geometry. The results obtained suggest the impossibility of extending the protection along the whole tube length; therefore, other protection methods are considered.

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“…El comportamiento de los latones en medio acuoso puede analizarse a través de sus correspondientes voltamperometrías [20][21][22][23] . Realizando un barrido desde potenciales catódicos hacia el potencial de corrosión, la disolución inicial forma Zn +2 a aproximadamente -1.1 V vs. SCE.…”

Section: Discussionunclassified