Fatigue performance of TBCs on Hastelloy-X substrate during cyclic bending

Our previous experiments with steel substrates confirmed that individual steps of conventional TBC deposition may influence fatigue properties of the coated samples differently. In this broader study, testing was carried out for TBC samples deposited on industrially more relevant Hastelloy-X substrates. Samples were tested after each step of TBC deposition process: non-coated, grit-blasted, bond-coated (NiCoCrAlY) and bond-coated + top-coated (YSZ). Conventional atmospheric plasma spraying with gas stabilized plasma torch was used for deposition of both bond-coat and top-coat. In addition, for one half of the samples, the bond-coat was prepared by consecutive combination of HVAF and APS process. Samples were tested both as-sprayed and after 100 hour annealing at 980 °C, which should simulate in-service conditions. Obtained results showed that different fatigue performance may be expected for various stages of the TBC deposition as well as due to the variation of the deposition process and sample temperature history.