An Overview of Rare Earth-Doped Ceramic Thermal Barrier Coatings for High-Temperature Performance of Nickel-Based Superalloys

Abstract

Superalloys are high-performing alloys and serve as an important class of structural material for utility in gas turbine key components where high temperatures and pressures are involved. However, prolonged exposure to severe oxidation causes material degradation, which eventually affects the mechanical properties of alloys and results in component failure. Therefore, the material failure at high temperatures can be minimized by surface treatments such as the provision of coatings. On account of protecting the metal components such as gas turbine blades and combustion chamber structures that are subjected to high temperatures, the method of provision of thermal barrier coatings (TBCs) becomes mandatory. The coating extends the life of the component by lowering the oxidation and thermal fatigue, at the same time enhancing the substrate durability by providing excellent thermal insulation to the gas turbine components, to make them operate at higher temperatures. Investigations were conducted on several coating methods, including plasma spray, electron-beam physical vapor deposition with bond coat, and topcoat materials, on the superalloy substrate materials. This review focuses on thermal barrier coating processes, the new coating materials, their property at high-temperature conditions, and subsequent failure mechanisms during their utility in gas turbine applications.