The Measurement of Residual Strains Within Thermal Barrier Coatings Using High‐Energy X‐Ray Diffraction

The residual strains through the entire thickness of the zirconia layer of pristine and heat‐treated thermal barrier coatings (TBCs) were mapped to help elucidate the failure mechanisms of TBCs. The strains were measured using 80.72 keV synchrotron radiation and a transmission geometry. The heat‐treated TBC showed that a compressive strain formed in the zirconia layer of the TBC on cooling but this strain was diluted and reversed by the oxidation‐driven expansion of the underlying metals. It also showed large (0.0024) out‐of‐plane tensile strains in the zirconia layer just above its interface with a thick underlying oxide layer.