The electrode potential is one of the most important parameters in the thermodynamics and kinetics of corrosion. This article discusses the fundamentals of electrode potentials and illustrates the thermodynamics of chemical equilibria by using the hydrogen potential scale and the Nernst equation. It describes galvanic cell reactions and corrosion reactions in an aqueous solution in an electrochemical cell. The article explores the most common cathodic reactions encountered in metallic corrosion in aqueous systems. The reactions included are proton reduction, water reduction, reduction of dissolved oxygen, metal ion reduction, and metal deposition. The article also presents the standard equilibrium potentials measured at 25 deg C relative to a standard hydrogen electrode for various metal-ion electrodes in a tabular form.

Electrode potential is a key parameter in the thermodynamic and kinetic processes that drive aqueous corrosion. This article discusses the complexities associated with measuring electrode potential and explains where and how to use reference electrodes to improve measurement accuracy. It describes a three-electrode approach that compensates for measurement error stemming from nonequilibrium conditions. It also examines electrode materials and behaviors and offers insights on selection and operating conditions.

Principles of metallic corrosion play a fundamental role in developing industrial processes that employ corrosion for constructive purposes. This article examines the changes in kinetics that occur with differentially small potential changes around the equilibrium electrode potentials of two reversible electrodes, such as copper and silver electrodes, in an electrochemical system. It provides a schematic illustration of a reversible cell with copper and silver electrodes to determine a reversible cell potential between the electrodes. An electrode becomes irreversible when the electrode reactions are displaced from equilibrium and the electrode potential is no longer at the equilibrium potential. The article describes irreversible cell potential by using galvanic cells, electrolytic cells, and corrosion cells.

This article discusses a tool for the conversion of measurements made against various reference electrodes at different temperatures. It reviews different electrode potential temperature coefficients, namely, isothermal temperature coefficient and thermal temperature coefficient. The article contains a table that lists the electrode potentials and conversion factors for various reference electrodes.

Overpotential is the current-producing potential difference between a nonequilibrium electrode potential and its corresponding equilibrium value for an electrode reaction. This article provides information on the overpotential of an electrode reaction. It contains a table that lists the values based on the electrode reaction. Because overpotential is a kinetic parameter and depends on current density, overpotential values presented are for a specific current density.

The article provides an introduction on the importance of alloying elements on corrosion behavior of nickel alloys and describes the applications of heat-resistant alloys to resist corrosion. It focuses on the metallurgical effects, mainly the effect of internal factors, including chemical composition and microstructure of the alloy, and the external factors, including electrolyte composition, temperature, and electrode potential, on the corrosion behavior of corrosion-resistant alloys. The article also discusses the implication of changing the alloy microstructure by second-phase precipitation, cold working, and cast and wrought forms on the corrosion behavior of high-nickel alloys.