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

ABSTRACT: This Phase II SBIR program seeks to develop a new thermal barrier coating (TBC) system with a diffusion barrier coating and low thermal conductivity (k) top coat for alleviating oxidation of the bond coat alloy and moisture induced delayed spallation (MIDS), along with increasing the thermal efficiency. 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. This failure is closely linked to the thermally grown oxide (TGO) layer on the bond coats during thermal exposures. Due to this fact, current efforts are focused on developing new bond coat alloys or top coats, but only minimal benefits have been achieved. We propose the development of new barrier coatings and a low k top coat to achieve a longer lifetime and a high thermal insulation. BENEFIT: Thermal barrier coatings (TBCs) are used for the hot sections of the aircraft engines to allow for higher use temperatures; however, the coating effectiveness is limited by unpredictable lifetimes and poor reliability. A new diffusion barrier coating along with a low k top coat could significantly reduce the TGO growth and adverse effects of water (MIDS). This would increase the TBC lifetime and predictability; the full incorporation of the new TBC into military aircraft and commercial engines is expected.