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

Pyrochlore-type (La0.8Eu0.2)(2)Zr2O7 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)(2)Zr2O7 were deposited by plasma spraying. Plasma sprayed (La0.8Eu0.2)(2)Zr2O7 coatings are composed of a defect fluorite-type phase and a t-ZrO2 phase. However, after thermal shock tests at 1250 degrees C for 32 cycles, (La0.8Eu0.2)(2)Zr2O7 coatings exhibit a pyrochlore-type structure. The thermal shock failure of double-ceramic-layer (La0.8Eu0.2)(2)Zr2O7/YSZ coatings mainly occurs at the interface between the (La0.8Eu0.2)(2)Zr2O7 and YSZ layers, and is not caused by thermal grown oxide layer from the bond coat. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.