Abstract
Abstract Since thermal barrier coatings (TBCs) for turbine blades suffer from bond coat oxidation and sintering of the ceramic top coat during service, quantification of TBC degradation by non destructive evaluation methods (NDE) is essential. IN617 substrates with standard NiCoCrAlY/PYSZ EBPVD TBCs were annealed at 1100 °C and measured by impedance spectroscopy. Parameters such as phase angle, total impedance, real and imaginary part were analyzed. To clearly separate bond coat oxidation from aging of the zirconia, freestanding ceramic top coats and ceramic free samples were analyzed as well. A straight correlation between the changes in the impedance spectra and the measured thickness of the thermally grown oxide was found.
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