Low radiative heat transfer realized by 8YSZ/LaAl₁₁O₁₈ composites for high-temperature applications

Lower thermal conductivity and improved mechanical properties at high temperatures have always been the principal focus of designing thermal barrier coating materials (TBCs). In the present study, layer-structured LaAl₁₁O₁₈ was introduced into 8 wt% yttria-stabilized zirconia (8YSZ) to further improve the thermal and mechanical properties of 8YSZ. Thus, a series of 8YSZ/LaAl₁₁O₁₈ composites were prepared by solid sintering at 1600 °C. The composition and microstructure analyses indicate excellent chemical compatibility between 8YSZ and LaAl₁₁O₁₈ at high temperatures. The composites demonstrate by ~ 61% reduction of total thermal conductivity at 1200 °C as compared to a single 8YSZ. The radiative heat transfer of composites decreases around ~ 96.3% due to substantial photon scattering, resulting from lower photon mean free paths. Meanwhile, relatively good fracture toughness and lower elastic modulus (about ~ 13.3%) are promising design features of the composites for engineering applications, such as TBCs.