COMPARISON OF ELECTRON-BEAM PHYSICAL VAPOR DEPOSITION AND PLASMA-SPRAY PHYSICAL VAPOR DEPOSITION THERMAL BARRIER COATING PROPERTIES USING SYNCHROTRON X-RAY DIFFRACTION

摘要

Electron-beam physical vapor deposition (EB-PVD) is widely used for the application of thermal barrier coatings (TBCs) to turbine blades in jet engines. An emerging method, plasma-spray physical vapor deposition (PS-PVD), is a hybrid technique whereby coatings can be applied via the liquid phase to form lamellar microstructures or via the vapor to form columnar micro structures similar to that of EB-PVD. In this study, PS-PVD and conventional EB-PVD coated samples of a columnar configuration were prepared and thermally cycled to 300 and 600 cycles. These samples were subsequently characterized in-situ, under thermal load using synchrotron x-rays. From the high-resolution x-ray diffraction (XRD) patterns, the residual and in-situ strain in the TGO layer was obtained during a thermal cycle. At high temperature, the TGO layer for both de- position methods displayed a constant near zero-strain for all samples as anticipated. In the samples with 300 thermal cycles, both deposition methods showed similar strain profiles in the TGO layer. For samples with 600 cycles, PS-PVD samples showed a more significant strain relief in the TGO at room temperature compared to similarly cycled EB-PVD samples. This could explain the coating lifetime performance between the two deposition methods. The findings support ongoing efforts to tune the manufacturing of PS-PVD coatings towards the goal of meeting or exceeding the performance of currently used coatings on jet engines. This will pave the way for more affordable high temperature coating alternatives that meet durability needs.