Remaining Life Prediction of Thermal Barrier Coatings Based on Photoluminescence Piezospectroscopy Measurements

Abstract

Nondestructive determination of the remaining life of thermal barrier coatings (TBCs) is highly desirable for components removed from service engines. Remaining life predictions for EB-PVD/Pt-Al TBCs cycled at two temperatures (1151°C and 1121°C) were made based on the thermally grown oxide stresses measured by the photoluminescence piezospectroscopy technique without knowing the test temperature. The predictions were compared using regression methods and neural network methods. It was found that both methods produce accurate life remaining predictions, but the neural network methods were superior. The lowest root-mean-square (rms) error and maximum absolute error for the prediction was 6.1% and 8.2%, respectively. For a data set with a 48.7% rms spallation life variation about the mean, the prediction results obtained are highly encouraging.