What is high temperature corrosion?

High-temperature corrosion is not a form of electrochemical corrosion that require a liquid electrolyte cell. The high-temperature corrosion mechanism causing by metals react directly with gaseous atoms in the atmosphere rather than ions in solution. Sometimes, this type of damage is called “dry corrosion” or “scaling.”

Electrochemical corrosion is a different concept, Mill scale created from HOT ROLL process

Alloys rely upon the oxidation reaction to develop a stable protective scale that resists further corrosion, such as sulfidation, carburization, and other forms of high-temperature attack.
Most of the time the corrosion mechanisms are determined by the dominant corrosion product(s), like oxidation (the general term for a variety of reactions) implies oxides, sulfidation indicates sulfides, sulfidation/oxidation indicates a combination of sulfides plus oxides, and carburization indicates carbides.

Hot corrosion is different with electrochemical corrosion
table

Corrosion resistance at high temperatures stems from a combination of thermodynamics and kinetics factors. Thermodynamics factors determine whether a corrosive reaction will proceed. Kinetics factors determine the rate at which the reaction may proceed.

Ref.
R.C. John, “Compilation and Use of Corrosion Data for Alloys in Various High-Temperature Gases,” CORROSION/99, paper no. 73 (Houston, TX: NACE, 1999).

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