Novel high-entropy (La0.35Gd0.35Y0.35Sm0.35Yb0.6)Zr2O7 thermal barrier coatings: Thermal cycling performance and failure behavior

The high-entropy ceramic (HEC) (La 0.35 Gd 0.35 Y 0.35 Sm 0.35 Yb 0.6 )Zr 2 O 7 has emerged as a strong candidate for thermal barrier coatings (TBCs) due to its exceptional thermal properties. We investigated the thermal shock resistance of HEC–lanthanum zirconate (LZ)/yttria partially stabilized zirconia (YSZ) (i.e., the HEC coating) and LZ/YSZ (i.e., the LZ coating) double-ceramic-layer TBCs fabricated via plasma spraying. During thermal shock testing at 1100 °C, the LZ coating failed after 60 ± 3 cycles, while the HEC coating had a considerably longer thermal cycling lifetime of 135 ± 5 cycles. The HEC coating's superior performance is attributable to its enhanced oxygen barrier properties and inherent lattice disorder; the former reduced the growth rate of the thermally grown oxide, and the latter increased lattice defects and distortion. These factors helped improve the thermal expansion coefficient and reduced interlayer thermal stress accumulation. Furthermore, the higher fracture toughness of the HEC layer impeded crack propagation, collectively enhancing the TBCs' thermomechanical shock resistance. These findings underscore the potential of (La 0.35 Gd 0.35 Y 0.35 Sm 0.35 Yb 0.6 )Zr 2 O 7 as a robust material for extending the service life of TBCs in high-temperature environments.