Parameter exploration of Yb2Si2O7 coatings prepared by Plasma Spray Physical Vapor Deposition

Ytterbium Disilicate (Yb₂Si₂O₇) coatings were prepared utilizing NASA GRC’s Plasma Spray-Physical Vapor Deposition (PS-PVD) rig with a recently installed XY motion stage. Parameters studied include primary and secondary gas flow rates, carrier gas composition and optimization and electric power settings. Special emphasis was given to torch motion for validation and optimization of the new equipment as well as the variability in microstructure and composition as they relate to spray parameters, including inter-run variability. Environmental barrier coatings (EBCs) exhibited a range of compositions from a mixture of monosilicate/disilicate to disilicate with excess SiO₂. Single and dual layer EBCs were evaluated with X-ray diffraction and scanning electron microscopy. Steam oxidation was performed at high temperature in 90% H₂O/O₂ to determine durability of these coating systems.