Mechanical properties of YSZ thermal barrier coatings with segmented structure

Traditional and modified Y₂O₃ stabilised zirconia (YSZ) thermal barrier coatings (TBCs) on nicked based superalloy DZ125 were produced by atmospheric plasma spray. In addition to the thermal properties, the mechanical properties of ceramics are also very important for superior TBCs. The mechanical properties of the sprayed coatings at room temperature, including microhardness, Young's modulus, fracture toughness and tensile strength, were evaluated. The Young's modulus and microhardness of the segmented coating were measured to be about 72 and 8 GPa, relatively higher than those of the non-segmented coating respectively. The fracture toughness was determined by an indentation technique. The values of 1·7–2·0 MPa m^1/2 for the traditional YSZ coatings are relatively lower than the values for the modified YSZ coatings 2·0–2·3 MPa m^1/2. The lower porosity and better lamellar bonding of the segmented coating could be responsible for the improvement of the mechanical properties.