Plasma-sprayed La2Ce2O7 thermal barrier coatings against calcium–magnesium–alumina–silicate penetration

As one of promising thermal barrier coating (TBC) candidates, La2Ce2O7 (LC) has attracted increasing attention because of its low thermal conductivity and potential capability to be operated above 1250 °C. In this paper, the microstructure evolution and mechanical properties of the plasma-sprayed LC TBC with calcium–magnesium–alumina–silicate (CMAS) glassy deposits at 1250 °C were investigated. Due to chemical reaction between the CMAS deposits and LC coating, a dense sealing layer, mainly composed of Ca2(LaxCe1−x)8(SiO4)6O6−4x and CeO2, was formed on the coating after heat-treatment at 1250 °C and effectively prevented CMAS from further penetration. The interaction layer had the micro-hardness of ∼10–12 GPa, relatively harder than the LC coating.