Contemporary materials issues for advanced EB-PVD thermal barrier coating systems

The key issues for thermal barrier coating (TBC) development are high tempe rature capability and durability under thermal cyclic conditions as experie nced in the hot section of gas turbines. Due to the complexity of the syste m and the interaction of the constituents, performance improvements require a systems approach. However, there are issues closely related to the ceram ic top coating and the bond coat, respectively. Reduced thermal conductivit y, sintering, and stresses within the ceramic coating are addressed in the paper as well as factors affecting failure of the TBC by spallation. The la tter is primarily governed by the formation and growth of the thermally gro wn oxide scale and therefore related to the bond coat. A strategy for lifet ime assessment of TBCs is discussed.