ISO 21456:2025

This document describes the test method for the determination of the residual stress of the TGO layer in thermal barrier coating by photoexcitation fluorescence piezoelectric spectroscopy. This test method requires that there must be a Cr element in the bond coat of the thermal barrier coating, i.e., Cr element shall exist in the TGO layer. This test method of determining the residual stress in the TGO layer of the thermal barrier coating system is not limited by the preparation method of the thermal barrier coatings. Particularly, the thermal barrier coating system prepared by EB-PVD has a better effect. This method provides guidance on determining reliable estimates of residual stresses from fluorescence spectral data and estimating uncertainties in the results.