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

Abstract

The effect of substrate rotation speed on the phase forming behavior and microstructural variation of 8 wt% yttria (Y 2 O 3 ) stabilized ZrO 2 (8YSZ) coatings as a thermal barrier coating has been investigated. 8YSZ coatings with 100 ~200 µm 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 o C. 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.

Microstructure Refinement of EB-PVD Gadolinium Zirconate Thermal Barrier Coatings to Improve Their CMAS Resistance

“…Substrate temperature and rotation speed have already proven to be decisive parameters for modifying the microstructures of EB-PVD TBCs [31,[34][35][36][37]. Jesuraj et al studied the effect of the substrate temperature on GZO [34] and Lanthanum zirconate [35] TBCs in a non-rotational EB-PVD coating process on nanomechanical properties and could observe an improved coating adhesion, higher hardness and Young's modulus for coatings deposited at 700 • C compared to lower substrate temperatures of 500 • C and 600 • C. However, due to the stationary positioning and the lower substrate temperatures, a significantly different microstructure was achieved compared to the present TBCs.…”

Analytical Model of the Process of Thermal Barrier Coating by the MO CVD Method

“…One of the well-proven ways of solving this problem is to use a rotating substrate that is streamlined by a reagent impinging jet. The morphology of the 7YSZ crystallite can be controlled by varying the rate of substrate rotation during deposition [16]. In this case, the content of phases in the columnar structure of 7YSZ remains almost constant.…”