Effect of Sc2O3 doping on YSZ TBCs: Morphologies, phase composition, mechanical properties, and high-temperature oxidation resistance

Y2O3 stabilized ZrO2 thermal barrier coatings (YSZ TBCs) and Sc2O3 and Y2O3 co-stabilized ZrO2 thermal barrier coatings (ScYSZ TBCs) were prepared by atmospheric plasma spraying technology, and then a high-temperature oxidation experiment was carried out at 1100 °C. Whereupon the morphologies, phase composition, and mechanical properties of YSZ ceramic coating and ScYSZ ceramic coating after different high-temperature oxidation time, as well as the high-temperature oxidation resistance of YSZ TBCs and ScYSZ TBCs, were comparatively studied. The results showed that after high-temperature oxidation, ScYSZ ceramic coating presented slighter cracking and exhibited better sintering resistance. After high-temperature oxidation, the phase composition of both YSZ ceramic coating and ScYSZ ceramic coating was still a single T' phase, and their interplanar spacing became larger; nevertheless, the interplanar spacing of ScYSZ ceramic coating was smaller than that of YSZ ceramic coating. After high-temperature oxidation, ScYSZ ceramic coating had higher hardness, smaller elastic modulus, and smaller fracture toughness. In addition, ScYSZ TBCs exhibited better high-temperature oxidation resistance according to the morphology, equivalent thickness, high-temperature oxidation kinetics, and high-temperature oxidation thermodynamics of TGO.