Lanthanum-cerium Oxide Thermal Barrier Coatings Prepared by Atmospheric Plasma Spraying

Lanthanum-cerium oxide(La2Ce2O7,LC) thermal barrier coatings(TBCs) were prepared by atmospheric plasma spraying(APS).The actual composition of the as-sprayed coating is La2Ce1.66O4.32,due to the volatilization of CeO2 phase during the spray process.A little decomposition of the LC coating takes place after annealing at 1400℃ for 240h.The thermal conductivity of bulk LC material is about 0.51W/(m·K) at 1000℃,which is one fourth of that of typical bulk YSZ.The coefficient of thermal expansion(CTE) of the LC coating ranges from 10×10-6K-1 to 13×10-6K-1 at the temperature from 450℃ to 1100℃,which is relatively higher than that of the YSZ coating.Dilatometric measurements show that there is slight shrinkage in the coating till 1250℃,however,a remarkable sintering process happens during holding period at 1250℃.A spallation of the LC TBC occurs after 60 cycles at 1100℃ by typical delaminating cracking within the LC topcoat.