The mechanical response of three EB-PVD thermal barrier coating microstructures

The mechanical response of as-received thermal barrier coating specimens with three different microstructures was evaluated. Specimens consisted of rectangular bars of Inconel 617 substrates with NiCoCrAlY bond coats and EB-PVD zirconia top coats. The deposition conditions had been varied to produce columnar top coat microstructures with three different column sizes. Scanning electron microscopy, optical microscopy, and X-ray diffraction analyses were used to characterize the microstructures. Four-point bend experiments were performed with the top coat under either tension or compression. In situ microscopy identified the damage formation and propagation modes, and acoustic emission analyses also identified differences in the responses of each microstructure.