Hot corrosion studies on plasma sprayed bi-layered YSZ/La2Ce2O7 thermal barrier coating fabricated from synthesized powders

摘要

La2Ce2O7 (LCO) with a pyrochlore structure has been considered as a propitious thermal barrier coating (TBC) system possessing high temperature (>1200 degrees C) phase stability. In the present study, double ceramic layer of yttria stabilized zirconia (YSZ) and lanthanum cerium oxide (La2Ce2O7, LCO) TBCs are fabricated by atmospheric plasma spraying (APS). Individual LCO and 8YSZ and bilayered LCO/YSZ coatings are developed using flowable YSZ and LCO powders synthesized by co-precipitation and combustion routes respectively and are characterized for phase and microstructure. The coatings subjected to hot corrosion (Na2SO4+V2O5 salt at 910 degrees C for 30 h) are characterized by X-ray Diffractometry and Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy. XRD shows the phase transformation of YSZ from tetragonal to monoclinic zirconia accompanied by the formation of LaVO4 and YVO4 as hot corrosion products. Considerable decrease in volume fraction of monoclinic zirconia phase has been observed for bilayered LCO/YSZ coating compared to 8YSZ single layer. (C) 2017 Elsevier B.V. All rights reserved.