EB-PVD processing of pyrochlore-structured La2Zr2O7-based TBCs

New ceramic thermal barrier coating (TBC) compositions superior to state-of-the-art PYSZ material are considered to overcome the problems related to phase stability and service-induced sintering within the columnar feather-like structure of current EB-PVD TBCs. Among those candidates for gas turbine applications, the pyrochlore-structure based TBCs, e.g. undoped and RE-oxide doped La2Zr2O7 offer very attractive properties. This work describes the fabrication and refers to the relations regarding manufacture and microstructure of two La2Zr2O7-coatings, deposited by single source EB-PVD processing. The compositions contain an undoped La2Zr2O7-coating and an Y2O3-doped La2Zr2O7-coating. The aspects leading to the successful manufacture of a homogeneously aligned microstructure in EB-PVD TBCs rely on the careful control of deposition parameters as well as ingot (evaporation source material) quality. Hence, the microstructure of the EB-PVD La2Zr2O7–coating analyzed by SEM/EDX and XRD have been correlated with the processing conditions in order to understand the controlling parameters for achievement of these coatings.