Mechanical Properties Durability of Sc2O3-Y2O3 Co-Stabilized ZrO2 Thermal Barrier Materials for High Temperature Application

The poor phase stability of conventional 6–8 wt.% yttria-partially stabilized zirconia (YSZ) results in the formation of detrimental cracks in thermal barrier coatings (TBCs) as well as the decrease of fracture toughness, limiting its long-term application above 1200 °C. Here, we try to prove that a higher t′-phase stability is the prerequisite for the mechanical properties durability of ZrO2-based TBC materials. Compared with YSZ ceramic, 7.0 mol.% Sc2O3 and 0.5 mol.% Y2O3 co-stabilized ZrO2 (ScYSZ) shows a superior t′ phase stability at 1300 °C. In addition, the fracture toughness of ScYSZ is nearly stable after being annealed at 1300 °C for 0–40 h, while the value of YSZ gradually declines during the aging process. The stable fracture toughness of ScYSZ is closely related to its prominent t′ phase stability. The elastic modulus of ScYSZ is nearly unchanged and lower than that of YSZ. The excellent stability of the phase structure and mechanical properties makes ScYSZ a great potential material for next generation high-temperature TBCs.