ISO 21456:2025

This document specifies a test method for the determination of the residual stress of the TGO layer in thermal barrier coating (TBC) by photoexcitation fluorescence piezoelectric spectroscopy. This test method specifies that there is a Cr element in the bond coat of the TBC. This test method to determine the residual stress in the TGO layer of the TBC system is not limited by the preparation method of the TBCs. Particularly, the TBC system prepared by electron beam-physical vapour deposition (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.