Phase Composition and Microstructural Responses of Graded Mullite/YSZ Coatings Under Water Vapor Environments

Abstract

Mullite-based systems have been considered as environmental barrier coatings (EBCs) for high temperature protection of Si-based ceramic (Si 3 N 4 , SiC) substrates against water vapor corrosion, for application in forthcoming turbine engines. Graded mullite/Y-ZrO 2 composites plasma sprayed over Hexoloy SiC substrates were analyzed as EBCs. All feedstock materials were purposely prepared and singular spraying conditions were used to assure superior crystallization. The different coated specimens were subjected to temperatures of 1300°C for 100-500 h under water vapor environment. The effect of water corrosion on the exposed coatings was investigated by focusing on their phase and microstructure changes.

Hot corrosion behaviour of the γ‐Y2Si2O7 ceramic exposed to NaVO3 or V2O5 molten salt

“…[3][4][5][6][7] Environmental barrier coating (EBC) can establish a barrier between the hot-end structural components and the harsh environments in the engine, which can effectively prevent or reduce the influence of the harsh environment in the engine on the material properties of the hot-end structural components. [8] Mullite, [9] mullite with yttriastabilised zirconia [10] and (1 − x)BaO-xSrO-Al 2 O 3 -2SiO 2 (BSAS, 0 ≤ x ≤ 1) [1] are the earlier materials used in EBCs. However, these EBC materials have high recession rates in combustion environments and cannot meet the requirements of EBCs.…”