Rare Earth Oxide Applications in Ceramic Coatings for Turbine Engines

Ceramic coatings containing rare earth oxides (REO) play a critical role in enabling high performance and efficiency in gas turbines used for power generation and propulsion. To meet evolving performance constraints, current and next-generation coating architectures employ a wide range of material systems containing larger fractions of REO compared to prior coating technologies. This chapter reviews the application requirements, design considerations and typical architectures for the thermal barrier coatings (TBCs) used to protect metal alloys and the environmental barrier coatings (EBCs) used to protect ceramic composites. It then introduces key materials families based on rare earth aluminates, hafnates, silicates, zirconates and related systems. Finally, the chapter discusses the techno-economic considerations for selection of the material system and REO constituent, and the outlook toward new materials and future coating systems.