Investigation of Isothermal Oxidation Behavior of Thermal Barrier Coatings (TBCs) Consisting of YSZ and Multilayered YSZ/Gd2Zr2O7 Ceramic Layers

Rare-earth zirconates have a big potential as top coat material of TBCs due to their superior high-temperature properties. TBCs are usually produced by thermal spray methods or electron beam physical vapor deposition (EB-PVD) techniques. Cold gas dynamic spray (CGDS) is a promising deposition method for production of dense and non-oxide bond coat compared to other thermal spray processes, while EB-PVD process provides good adhesion and strain tolerance for top coating layers of TBCs. In this study, in order to observe the effect of Gd2Zr2O7 on the oxidation behavior of TBCs, CoNiCrAlY was sprayed on substrate material using the CGDS method, afterward, yttria-stabilized zirconia (YSZ) and YSZ/Gd2Zr2O7 were deposited using EB-PVD technique. After deposition, specimens were isothermally oxidized in a high-temperature furnace at 1100 A degrees C for 8, 24, 50, and 100 h. Microstructures of oxidized samples were examined and thermally grown oxide layer of TBCs were comparatively evaluated.