Dense yttria-stabilized zirconia coatings fabricated by plasma spray-physical vapor deposition

Plasma spray-physical vapor deposition (PS-PVD) is a novel technique which can offer new opportunities to obtain advanced microstructures. In this study, dense yttria-stabilized zirconia (YSZ) coatings were deposited using PS-PVD with proper parameters. The dependencies of the microstructure of the as-sprayed coatings on axial spray distance and radial position were discussed. Four typical coatings were selected for the current work. The corresponding microstructures, phase compositions and mechanical properties were studied in detail. These as-sprayed coatings had dense lamellar or lamellar/columnar hybrid microstructures, the lowest porosity was 0.44%. Both monoclinic and tetragonal zirconia were detected in the as-sprayed coatings. The distribution of yttrium was not homogeneous, especially in the coatings deposited at shorter spray distance. Furthermore, oxygen got lost partly during the spraying process with decreasing spray distance. The hardness (H) and Young's modulus (E) of the coatings changed simultaneously with the different microstructures. The maximum values of H and E were 16.6±0.6 and 234.3±10.1 GPa respectively, which were found in the densest coatings. The dense PS-PVD ceramic coatings might be applicable in anti-corrosion fields (such as alkali corrosion, marine corrosion and hot corrosion).