Effect of Substrate Rotation on the Phase Evolution and Microstructure of 8YSZ Coatings Fabricated by EB-PVD

The effect of substrate rotation speed on the phase forming behavior and microstructural variation of 8 wt% yttria (Y₂O₃) stabilized ZrO₂ (8YSZ) coatings as a thermal barrier coating has been investigated. 8YSZ coatings with 100 ~ 200 ㎛ thickness were deposited by electron beam-physical vapor deposition onto a super alloy (Ni-Cr-Co-Al) substrate with a bond coating (NiCo-CrAlY). The width of the columnar grains of the 8YSZ coatings increased with increasing substrate rotation speed from 1 to 30 rpm at a substrate temperature range of 900 ~ 950℃. In spite of the different growth behaviors of coatings with different substrate rotation speeds, the phases of each coating were not changed remarkably. Even after post heat treatments with various conditions of the coated specimens fabricated at 20 rpm, only a change of color was noticeable, without any remarkable change in the phase or microstructure.