Piezospectroscopy Measurements of Thermal Barrier Coating Systems

This research presents results for spectroscopy studies on thermal barrier coating layered systems. The primary study was conducted on a nickel superalloy cylindrical sample, with a multi-layer system deposited via electron beam physical vapor deposition (EB-PVD) including a thermally grown oxide (TGO) and partially stabilized zirconium oxide (YSZ) top coat. Selected spectroscopy studies were investigated via Raman Spectroscopy and Photo-Luminescence Spectroscopy with a 532 nm diode laser and Renishaw Ramascope via a 10x fiber optic probe. Readings were collected around the circumference in 10 degree increments, and yielded the variation of the materials’ characteristic peaks from which a residual stress profile was determined around the circumference for multiple layers. The findings uniquely show the stress profile of the YSZ and TGO during early cycling, and present variations around the circumference for varying locations in the testing area. Results showcase the degree of uniformity during this stage of development. The outcomes of these studies will advance the understanding of TBC residual stress during early cycling for cylindrical specimens, and provide valuable material response information for system modeling