Study of toughening behavior of SiC whiskers on 8YSZ thermal barrier coatings

The embrittlement of thermal barrier coatings (TBCs) in a high-temperature service environment inhibits the ability of the top-coat to resist crack initiation and propagation, in which the cracks are generated by erosion or wear of particles, limiting the service durability of TBCs. This study was based on the preparation of SiC whiskers (SiCw) / Y2O3 partially stabilized ZrO2 (YSZ) integrated composite powder, and the SiCw/YSZ composite TBCs was prepared through the atmospheric plasma spraying (APS) to improve the toughness of the top-coat. The effects of SiCw on the fracture toughness, tribological properties, erosion resistance and bending strength of the coatings were studied. The results showed that the fracture toughness of the composite coating with a SiCw length-to-diameter ratio (L/D ratio) of 250 was 24.6 % higher than the YSZ coating. Moreover, the composite coating presented excellent performance in wear, erosion, and resistance to crack propagation and spallation. The low amplitude of the Weibull modulus m of hardness distribution of the doped coating proved the stability effect of SiCw on the reinforcement and toughening of the coating.