Abstract
Environmental barrier coatings (EBCs) play a critical role in mitigating the degradation of SiCf/SiC ceramic matrix composites (CMCs) in complex combustion environment, and improve the service life of thermal engine components. In this paper, by adjusting the parameters of atmospheric plasma spraying (APS), the spraying process of ytterbium disilicate (Yb2Si2O7) under a lower power has been optimized. A two-layer EBC system consisting of ytterbium disilicate and silicon is prepared on the SiCf/SiC composite substrate by using optimized technological parameters. The thermal resistance and water oxygen corrosion resistance of such two-layer EBC system are investigated. The results indicate that the current ytterbium disilicate/silicon EBC system exhibits good phase stability, excellent water vapor and oxygen corrosion resistance. However, the exposed silicon bonding layer tends to generate an excessive thermal growth oxide (TGO) layer known as SiO2, leading to an early spallation of the coating.
Highlights
The improvement of thrust-to-weight ratio of advanced aero-engines is highly dependent on the development and application of advanced materials
The results indicate that the current ytterbium disilicate/silicon Environmental barrier coatings (EBCs) system exhibits good phase stability, excellent water vapor and oxygen corrosion resistance
The atmospheric plasma spraying (APS) parameters are optimized in the low power level
Summary
The improvement of thrust-to-weight ratio of advanced aero-engines is highly dependent on the development and application of advanced materials. It is necessary to deposit environmental barrier coatings (EBCs) on the surface of SiCf/SiC composite components to physically isolate components from the complex engine environment and extend the service life of the CMC components [6] [7]. NASA [8] [9] is leading the research on EBCs, and the research in China has made great progress in these years. APS technology has been widely used as the preparation of EBCs because of its simple operation, high efficiency and low cost. High spraying power leads to the volatilization of Si causing the deviation of coating composition. After optimization of APS parameters, the microstructure, phase composition, thermal stability and water vapor corrosion resistance of this EBCs system were characterized
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