Effects of feedstock structure and spraying power on microstructure, mechanical and thermal properties of yttria‐stabilized zirconia coatings

Abstract The influence of spraying power and YSZ (yttria‐stabilized zirconia) feedstock powder on coating microstructures and properties has been demonstrated in the case of atmospheric plasma‐sprayed YSZ coatings. Two types of YSZ powders, conventional and hollow‐structural feedstock, were investigated. Microstructural defects of as‐deposited YSZ coatings, such as porosity, interlamellar pores, and intrasplat cracks, were analyzed from the top view and fracture surfaces. Compared to conventional YSZ coating, the YSZ coating produced from hollow‐structural feedstock demonstrated distinct features, including high porosity and good mechanical interlocking. However, with an increase in spray power, the porosity of almost all YSZ coatings decreased. Hollow‐structured YSZ coating exhibits highly mechanical compliance and lower thermal conductivity as referenced to conventional YSZ coating. The processing parameters of conventional and hollow‐structured YSZ coatings were optimized considering the correlations among processes, microstructure features, and properties in combination with adopting optimized feedstock powders, providing opportunities for continuing optimization of thermal barrier YSZ coatings.