The Influence of Heat Treatment Presence and Sequence on Oxidation Resistance of YSZ Thermal Barrier Coatings

This study investigates the influence of heat treatment on the oxidation resistance of thermal barrier coatings. The coating systems examined incorporate an APS YSZ topcoat and a HVOF NiCo bond coat. Isothermal heating tests were conducted to determine how heat treat sequences affect interdiffusion between the bond layer and substrate and the microstructure of the bond coat and ceramic topcoat. Before and after heating, specimen cross-sections were studied by SEM and EDX analysis. Preliminary results indicate that the oxidation resistance of YSZ-NiCo coatings can be improved with a suitable heat treatment, in some cases, extending elevated-temperature service life by as much as 500 h. Abstract only; no full-text paper available.