Experimental testing and FEM calculation of impedance spectra of thermal barrier coatings: Effect of measuring conditions

Abstract Impedance spectroscopy (IS) is a nondestructive evaluation tool for examining degradation of thermal barrier coatings used in the hot section of aeroturbine engines. Key factors controlling IS include microstructure features and measuring conditions. Here we systematically investigate the effect of several measuring conditions on IS via experiment and finite element method (FEM). The results show that the most significant factor affecting the spectra is the temperature, followed by the silver electrode area, while both exert more obvious effect than the voltage amplitude. Furthermore, suitable values for the measuring parameters are optimized based on the results of experiment and FEM calculation.