Effects of piezo-spectroscopic coefficients of 8 wt.% Y2O3 stabilized ZrO2 on residual stress measurement of thermal barrier coatings by Raman spectroscopy

By using specially designed freestanding 8 wt.% Y2O3 stabilized ZrO2 (8YSZ) specimens, a linear relationship is found between the Raman peak shift, Δω, and applied uniaxial compressive stress, σ̅u, i.e., Δω = Πuσ̅u with Πu being the piezo-spectroscopic coefficient. The linear relationship is used to determine the in-plane residual stress in air plasma-sprayed 8YSZ thermal barrier coatings (TBCs). It is shown that the Πu of the 8YSZ is an exponential function of the thermal cycle N for a given thermal cycling process: Πu = 37.6exp(− N/25.9) + 13. Based on these two relationships, the actual residual stress of 8YSZ TBCs determined by the Raman spectroscopy method is quantitatively consistent with that obtained by the X-ray diffraction.