59649 - Synchrotron X-Ray Diffraction to Quantify In-Situ Strain on Rare-Earth Doped Yttria-Stabilized Zirconia Thermal Barrier Coatings 

The interest for multifunctional coatings that can be integrated into gas turbine engines for in-situ temperature measurements or health monitoring and without disrupting standard thermomechanical properties has been growing over the past few years. The addition of specific rare-earth dopants into standard thermal barrier ceramic top coat materials such as yttria-stabilized zirconia can provide luminescence sensing capabilities. The thermomechanical performance and durability of such smart coatings in relevant engine environments still remains to be evaluated. In this study, highly luminescent rare-earth doped yttria-stabilized zirconia and state-of-the-art yttria stabilized zirconia coatings were manufactured to characterize the effects of the embedded rare-earth dopants on coating internal strains and to quantify and compare their high temperature response using synchrotron X-ray diffraction. In-situ strain measurements were performed at intervals along the depth of the coatings to evaluate specific strain at key locations such as the interface between the rare-earth doped layer and the standard yttria-stabilized zirconia layer or at the interface with the bond coat. The results show great promise for the safe utilization of multi-functional luminescent coatings as the low concentration of rare-earth elements in the coatings was found to show limited impact on the strains, especially at temperature closer to gas turbine operating temperatures.