Low Conductivity for Thermal Barrier Coatings (TBCs)

Higher inlet temperatures for turbine engines will provide significant benefits in fuel efficiency and performance for both military and commercial air vehicles. To accomplish this goal, new generation thermal barrier coatings (TBCs) with superiorreliability and durability will be needed. The currently-used zirconia-based TBCs do not adequately meet thermal conductivity requirements and they suffer from thermomechanical degradation during exposure at elevated temperatures. In this effort, a novelcrystal chemistry approach is being explored to examine a new family of layered perovskites as TBC materials. Key properties of these highly anisotropic materials include low thermal conductivity (0.7 W/m-K @ 13000C), tailorable CTE to potentially matchsubstrate for minimizing residual stress, and inherent strain tolerance to potentially accommodate stresses induced during thermal exposure and cycling. During Phase II, coatings of proposed material will be produced by plasma spray technology. The focuswill be to optimize coatings for obtaining thermally stable and desired microstructure, crystallographic texture, and thickness to yield durable and reliable TBCs that also meet Army's targeted requirements for low thermal conductivity. Thermal cyclingtests will be conducted on coated superalloy coupons to determine coating performance and durability. The work will be conducted in collaboration with a turbine engine manufacturer.