Multicomponent rare-earth cerate and zirconocerate ceramics for thermal barrier coating materials

Thermal barrier coatings can improve the energy efficiency of industrial or aircraft gas turbines by increasing the operation temperature. In this study, new TBC materials, namely multicomponent rare-earth cerate (Sm0.2Eu0.2Tb0.2Dy0.2 Lu-0.2)(2)Ce2O7 (5RC) and zirconocerate (Sm0.2Eu0.2Tb0.2Dy0.2Lu0.2)(2)ZrCeO7 (5RZC) ceramics were synthesized by solid-state reaction sintering. 5RC and 5RZC had a homogeneous rare-earth element distribution and a pure fluorite structure up to at least 1400 degrees C, hence, showing good phase stability. The coefficient of thermal expansion of 5RC appeared to have a linear increase, reaching 12.60 x 10(-6) K-1 at 1200 degrees C without a sharp increase at low temperatures, as observed for several single-component rare earth cerates. The thermal conductivity was also reduced in multicomponent 5RC and 5RZC. Moreover, 5RZC exhibited a better sintering resistance than 5RC. The doped Zr reduces the volatilization of ceria and enhances the stability of 5RC. As conclusion, the multicomponent rare-earth cerates 5RC and 5RZC are potential thermal barrier coating materials.