Process-Property-Performance Interplay in Thermal Barrier Coatings on Varying Substrate Geometry

The microstructural features of an air plasma sprayed (APS) ceramic thermal barrier coating (TBC) can show a wide range of variability when transitioning from flat planar surfaces to more complex geometries. Differences in microstructure arises from the interaction of the spray plume with the substrate, which differs greatly between planar disks and rods. These geometrical differences can also affect the failure of TBCs when subjected to furnace cycling via a change in failure mechanisms. In this study, disk and rod geometry TBCs were produced on CM247 substrates and characterized for their thermal cycling response. The top coat microstructures were deliberately varied via processing to evaluate coatings with the same chemistry (7YSZ) but different microstructure. Concurrently, a study was conducted to ensure that the coatings deposited would be comparable between the disks and rods. In addition, bond coat properties were also varied through the use of different types of deposition processes. The results show that the microstructure requirements for optimal durable performance differs greatly between the two geometries.