Hydration Tolerant, low Thermal Conductivity (K) Thermal Barrier Coatings

ABSTRACT: This Small Business Innovation Research Phase I project seeks to develop a new diffusion barrier layer that allows for a hydration tolerant thermal barrier coating (TBC) system, along with an outstanding oxidation resistance of the bond-coat. TBCs have been applied to the hot sections of aircraft turbine engines to increase engine efficiency and to extend the life of metal components; however, they have not been fully integrated to the engine design due to the potential catastrophic failures at the interfaces where crack formation takes place. Moreover, the state-of-the TBC system seems vulnerable to moisture, leading to spallation of the top TBC layer, termed moisture-induced delayed spallation (MIDS). Due to this fact, current efforts are focused on developing new alloys or barrier coatings, but only minimal advancements have been achieved. We propose the development of new barrier coatings based on yttrium aluminates. The project is composed of the development of a robust coating process and experimental verification of water and oxidation resistance, as well as chemical inertness. BENEFIT: TBCs are used for the aircraft engines but are currently limited by unpredictable lifetimes and poor reliability. A new diffusion barrier coating based on yttrium aluminates could significantly reduce the adverse effects of water, such as moisture-induced delayed spallation (MIDS), as well as TGO growth. The reliability and life of the TBC can be improved, and full incorporation into commercial engines will be expected.