Thermochemical compatibility between La2(Ce1-xZrx)2O7 and 4 mol% Y2O3 stabilized zirconia after high temperature heat treatment

Abstract La2Ce2O7 (LC) has attracted extensive attention as promising material for thermal barrier coatings (TBCs) in next generation gas turbines due to its outstanding thermophysical properties. To eliminate the reaction between LC and thermal grown oxides (TGO), yttria stabilized zirconia (YSZ) is usually employed as the interlayer to form LC/YSZ double-layered structures. However, recent studies have revealed that chemical stability of LC and YSZ system deteriorates at high temperatures, which may hinder the application of LC as TBCs. To address this problem, the chemical compatibility between La2(Ce1-xZrx)2O7 (LCZ) and YSZ at high temperatures was investigated in this work via experiments and atomistic simulations. Results reveal that chemical compatibility increased with the increase in Zr content of LCZ. Corresponding molecular dynamic simulations further verify that the increase in Zr content of LCZ system would reduce Gibbs free energy of LCZ-YSZ composite system. Moreover, common phenomena in LC-YSZ system, such as abnormal grain coarsening and intensive pore diffusion, were effectively suppressed in LCZ-YSZ composite, due to enhanced high temperature chemical compatibility. Results also indicate that the addition of buffer layer, i.e., LCZ-YSZ composite, can effectively improve chemical stability of TBCs based on double layered LC/YSZ.