Comparison of thermally cycled ps-pvd and eb-pvd thermal barrier coatings - depth-resolved monoclinic phase evolution via synchrotron x-ray diffraction

Abstract

Thermal barrier coatings (TBC) are use to protect turbine components in hot sections of jet engines from their extreme surrounding temperatures (>1100◦ C). A current deposition technique that is used in industry, electron-beam physical vapor deposition (EB-PVD), creates a high quality ceramic coating with a columnar micrsotructure that is strain compliant and thermally resistant. An emerging deposition method, plasma-spray physical vapor deposition (PS-PVD), allows manufacturers to customize the microstructure by varying the process parameters, while having a shorter deposition time that lowers the cost of a potentially strain tolerant, single-layer coating. The mechanical and microstructural properties of PS-PVD coatings have yet to be fully understood. PS-PVD samples were made with processing parameters aimed to have a similar strain compliant columnar microstructure to those from EB-PVD. Through-depth monoclinic phase volume fraction (mPVF) in samples that were uncycled and thermally cycled for 300 and 600 hours was measured in-situ during a one-hour thermal cycle via high energy synchrotron X-ray diffraction (XRD). PS-PVD samples exhibited greater mPVF than EB-PVD samples, with a greater amount of mPVF in the middle of the YSZ. These results are the preliminary findings that are necessary for optimizing the PS-PVD processing parameters to obtain the strain compliant microstructure similar to that of EB-PVD.