High-temperature
High-temperature corrosion
High-temperature corrosion is a chemical attack from gases, solid or molten salts, or molten metals, typically at temperatures above 400 °C. There are Different types of high-temperature corrosion such as: Oxidation, Sulphidation, Carburization, Chlorination and Nitridation.
Thermodynamics
Most metals react spontaneously with the surrounding environment forming various corrosion products depending on the specific environment. Considering a bare metal surface in contact with oxygen (e.g. ambient air), the plots of the standard free energy of reaction (∆G0) as a function of temperature, commonly called Ellingham diagrams, can help to visualize the relative stability of metals and their oxidized products In a similar manner diagrams describing the formation of metal chlorides, metal carbides, metal sulphides etc. can also be constructed.
Technology
Industrially, high-temperature corrosion is a significant issue. Any component that is exposed to a high temperature in a high temperature environment is potentially at risk. It is a major problem in various industries such as: Aerospace and gas turbines, Mineral and metallurgical processing, Chemical processing and Heat treating.