Insights into the primitives and sequence deposition mechanism of 7YSZ TBCs respectively by EB-PVD and PS-PVD

The deposition mechanism of 7YSZ (7 wt% Y2O3-ZrO2) thermal barrier coatings (TBCs) prepared by plasma spray–physical vapor deposition (PS-PVD) and electron beam–physical vapor deposition (EB-PVD) were investigated in detail. These coating primitives (grains) were deposited using atomic vapor. The PS-PVD primitives were short rod–shaped, while the EB-PVD primitives were needle-shaped. The PS-PVD coating primitives were ordered in the interior but disordered on the surface due to quenching under the influence of the plasma flow. However, the EB-PVD coating primitives were ordered from the interior to the surface. The feather-like columnar structure in PS-PVD was sequenced due to the vapor-liquid-solid mixed-phases deposition. In contrast, the needle-like columnar structure in EB-PVD was sequenced because of the single-vapor phase deposition. In addition, we investigated the effect of non-line sight deposition of PS-PVD on the coating, which can reveal the coating pattern on complex blade shapes. The results show that the deposition mechanism of 7YSZ TBCs can be divided into two stages, including primitives and sequences.