Process-Structure-Property Relationships in Advanced Thermal Barrier Coatings (TBC) Fabricated via Plasma Spray – Physical Vapor Deposition (PS-PVD)

Plasma Spray – Physical Vapor Deposition (PS-PVD) is a hybrid processing technique combining aspects of the two primary thermal barrier coating (TBC) deposition techniques; air plasma spray (APS) and electron beam – physical vapor deposition (EB-PVD).  PS-PVD can yield splat-like lamellar structures similar to traditional APS coatings, while low pressure and high power can enable partial and/or complete vaporization of feedstock material to form hybrid and PVD – columnar microstructures.  This study focuses on the process-structure-property relations of PS-PVD coatings composed of benchmark 7 wt% yttria stabilized zirconia (7YSZ) as well as more advanced compositions such as rare earth doped YSZ and rare earth pyrochlores (Gd₂Zr₂O₇).  Phase and microstructural analysis were performed using X-ray diffraction, optical profilometry, electron microscopy and image analysis.  Select PS-PVD coatings were then compared to similar compositions deposited via traditional APS and EB-PVD processes using erosion performance and thermal conductivity as test metrics.