The high-temperature corrosion processes that are most frequently responsible for the degradation of furnace accessories are oxidation, carburization, decarburization, sulfidation, molten-salt corrosion, and molten-metal corrosion. This article discusses each corrosion process, along with the corrosion behavior of important engineering alloys. It describes the corrosion of plating, anodizing, and parts of pickling equipment such as tanks, wirings and bus bars, racks, anode splines, pumps, and heaters.

Metals and ceramics exposed to high-temperature salt solutions are susceptible to a form of corrosion caused by fused salts accumulating on unprotected surfaces. This article examines the electrochemistry of such hot corrosion processes, focusing on sodium sulfate systems generated by the combustion of fossil fuels. It explains how salt chemistry, including acid/base and oxidizing properties, affects corrosion rates and mechanisms. The article also provides information on electrochemical testing and explains how Pourbaix methods, normally associated with aqueous corrosion, can be used to study fused-salt corrosion.

Molten salts, in contrast to aqueous solutions in which an electrolyte (acid, base, salt) is dissolved in a molecular solvent, are essentially completely ionic. This article begins with an overview of the thermodynamics of cells and classification of electrodes for molten salts: reference electrodes and indicator electrodes. It explains that corrosion in molten salts can be caused by the solubility of the metal in the salt, particularly if the metal dissolves in its own chloride. The article describes the factors that affect the corrosion of titanium, namely, the titanium chloride content of the magnesium chloride melt, magnesium or sodium content, and oxygen content of the product. It concludes with a discussion on the oxygen activity in the titanium metal product.

This article discusses two general mechanisms of corrosion in molten salts. One is the metal dissolution caused by the solubility of the metal in the melt. The second and most common mechanism is the oxidation of the metal to ions. Specific examples of the types of corrosion expected for the different metal-fused salt systems are also provided. The metal-fused salt systems include molten fluorides, chloride salts, molten nitrates, molten sulfates, hydroxide melts, and carbonate melts. The article concludes with information on prevention of molten salt corrosion.

This article provides a discussion on the fundamentals of corrosion thermodynamics. The discussion focuses on electrochemical reactions, molten salt corrosion thermodynamics, and geochemical modeling.

Molten salts, or fused salts, can cause corrosion by the solution of constituents of the container material, selective attack, pitting, electrochemical reactions, mass transport due to thermal gradients, and reaction of constituents and impurities of the molten salt with the container material. This article describes a test method performed using thermal convection loop for corrosion studies of molten salts. It discusses the purification of salts that are used in the Oak Ridge molten salt reactor experiment. The article also reviews the corrosion characteristics of nitrates/nitrites and fluoride salts with the aid of illustrations and equations.