Microstructural and Thermal properties of Plasma Sprayed YSZ Nano-Clusters Thermal Barrier Coatings

In the present study, a novel durable three layered thermal barrier coating (TBCs) were prepared using atmospheric plasma spray (APS) on Ni718 superalloy substrate consisting of the YSZ nano-clusters. In order to develop a functionally graded coating system, the non-transformable (t′) tetragonal YSZ nano-clusters (40 nm) were synthesized by a sol–gel process and characterized at the temperature 1200 °C for 100 h. NiCrAlY was used as bond coat. The developed coating system introduces a protective top layer of MoSi2 (top coat) for preventing diffusion of oxygen, oxidation of the bond coating, provides thermal insulation and protection against corrosion and high temperature erosion. Microstructural, thermal oxidation resistance, thermal shock and adhesion strength of TBCs were analyzed. Different properties of as-sprayed TBCs have no significant effect on thermal oxidation property. The TBCs have shown better thermal shock resistance but lower adhesion strength than the TBCs made of without MoSi2 layer.