Regional characteristics of YSZ coating prepared by expanded Ar/He/H plasma jet at very low pressure

7YSZ coatings were prepared by plasma spray - physical vapor deposition (PS-PVD) process based on a specific experiment design. The microstructures of 7YSZ coatings along the radial direction of Ar/He/H plasma jet were studied. The study found that the coatings prepared by PS-PVD process showed significant regional characteristics along the radial direction, which were divided into three zones, respectively defined as Vapor Phase Deposition Zone, Transition Deposition Zone and Accumulation Deposition Zone. The coatings have different structure characteristics changing gradually from the large columnar structure with cauliflower-like tops to the dense structure, which are closely related to the state and distribution of powder particles in the expanded Ar/He/H plasma jet. The central zone of Ar/He/H plasma jet can form columnar structure is about 80 mm in diameter. Based on the experiment results, a preliminary model about regional characteristics of 7YSZ coating depended on the state and distribution of the powder particles in expanded Ar/He/H plasma jet is proposed in this article. It is helpful to understand PS-PVD process and control coating properties in actual industry.