Changes in electrochemical impedance with microstructural development in TBCs

Thermal barrier coatings (TBCs) are improving the performance and efficiency of advanced gas turbine engines by allowing higher inlet temperature and insulation of critical hot-section components. Monitoring the integrity of TBCs prior to failure is critical to the overall performance of gas turbine engines and requires a robust nondestructive evaluation (NDE) technique. In this paper changes in electrochemical impedance with microstructural degradation of critical constituents in TBCs are summarized for the development of electrochemical impedance spectroscopy as an NDE technique for TBCs