Abstract:As the most widely used thermal barrier coating, the combined mechanical properties of YSZ, such as hardness, fracture toughness and modulus, have a significant impact on its service life and failure mode. In this study, atmospheric plasma spraying (APS) was used to prepare 7YSZ coatings and NiCoCrAlY bonding layers on the surface of nickel-based alloys, and nanoindentation and scanning electron microscopy (SEM) were utilized to analyze the changing law of nanomechanical properties of the 7YSZ coatings from the outside to the inside, and to determine the main factors that affect the nanomechanical properties of the 7YSZ coatings. The results showed that the hardness, fracture toughness and modulus of the 7YSZ coating on the outer surface were 7.5±0.9 GPa, 1.53±0.03 MPa·m1/2 and 121±13 GPa, respectively, which were slightly higher than those of the inner coating close to the bonding layer, which was attributed to the change of porosity and the stresses exerted by the bonding layer on the 7YSZ coating resulting in the decrease of its mechanical properties. Furthermore, the nanomechanical properties of 7YSZ coatings were quickly determined by nanoindentation testing, which provided a reference value for the analysis of micromechanical mechanisms.