Overview Oxidation ResistanceThis article examines the historical development of high-temperature, oxidation-and corrosion-resistant coatings, demonstrating how diffusion surface treatments, modified diffusion coatings, the design of M-Cr-Al-X corrosion-resistant overlay coatings, and the application of thermal-barrier coatings can be used to reduce the scaling (oxidation) rate of coated components. Future trends in hightemperature coating design are also reviewed, including the custom design of corrosionresistant alloys, smart overlay coating concepts, diffusion barriers, and the use of layered thermal-barrier coating structures.
INTRODUCTIONSurface engineering plays an important role in the operation of all hightemperature plants, whether for power generation, chemical processing, or component heat treatment. In its simplest form, the surface engineering of structural alloys results from the growth of a protective oxide, due to the selective oxidation of alloying additions within the alloy. The desire for higher operating temperature; improved performance; extended component lives; and cleaner, more fuel-efficient power plant/processes places severe demands on the structural materials used to construct such a high-temperature plant. As a result, many components operating at high temperature within such plants are coated or surface treated.The use of coatings, or surface treatments, permits the separation (or partial separation) of surface-and substrate-