Microstructure and Properties of Plasma-Sprayed Nanostructure ZrO₂-7%Y₂O₃ Thermal Barrier Coatings

The thermal barrier coatings (TBCs) were prepared on TiAl alloy surface by plasma spraying using conventional and nanostructure agglomerates ZrO2-7wt%Y2O3 ceramics powders as raw materials. The morphology, microstructure and microhardness of the coatings were investigated by means of scanning electron microscopy and microhardness tester. The tribological propereies and high-temperature oxidation resistance of the coatings were analyzed. The results show that the conventional ceramic coatings had a typical lamellar stacking characteristics. The nanostructure coatings exhibited two-phase structure, including the matrix phase recrystallized after nano particles completely melting and the embedded phase with partial melting nano particles. The surface hardness of nanostructure coating was 1 267.6 HV, and the friction coefficient was 0.8. The mass gain of the coating after oxidation at 850 ℃ for 100 h was 2.64 mg·cm-2.