Novel double-ceramic-layer (La0.8Eu0.2)2Zr2O7/YSZ thermal barrier coatings deposited by plasma spraying

Pyrochlore-type (La0.8Eu0.2)2Zr2O7 feedstocks prepared by spray drying have been used to produce ceramic thermal barrier coatings. Double-ceramic-layer thermal barrier coatings with a first layer of 8 wt% yttria-stabilized zirconia (YSZ) and a top layer of (La0.8Eu0.2)2Zr2O7 were deposited by plasma spraying. Plasma sprayed (La0.8Eu0.2)2Zr2O7 coatings are composed of a defect fluorite-type phase and a t-ZrO2 phase. However, after thermal shock tests at 1250 °C for 32 cycles, (La0.8Eu0.2)2Zr2O7 coatings exhibit a pyrochlore-type structure. The thermal shock failure of double-ceramic-layer (La0.8Eu0.2)2Zr2O7/YSZ coatings mainly occurs at the interface between the (La0.8Eu0.2)2Zr2O7 and YSZ layers, and is not caused by thermal grown oxide layer from the bond coat.