The 8 wt.% yttria-stabilized zirconia (8YSZ) thermal barrier coatings (TBCs) are widely used to protect hot superalloy components of gas turbine and jet engine. However, Cracks and pores in the 8YSZ coating would accelerate the oxidation of the bondcoat alloy and the corrosion of 8YSZ topcoat by molten salts and finally result in permanent failure of the TBCs. Hence, in this work, a sol-gel spin-coating method was employed to prepare a densea-Al_2O_3 film on the surface of air-plasma-sprayed 8YSZ coatings, in order to block the paths of cracks and pores while keeping the stress tolerance of 8YSZ coatings.The influences of the polyvinylpyrrolidone (PVP) and alumina content of the sol on the microstructure of the α-Al_2O_3 film were investigated. It is found that a sol with PVP addition amount of50mg/mL and alumina solid contentof 10%let to the achievement of a compact α-Al_2O_3 film. The positive results in this work would inspire more efforts to prepare dense films on TBCs and therefore improve their performance under service conditions.
展开▼
