Compositional and Microstructural Effects in the Protection of SiC Components in Water Vapor

Kowalski, Benjamin ; Harder, Bryan

关键词: AMORPHOUS MATERIALS;    CERAMIC MATRIX COMPOSITES;    DEGRADATION;    FAILURE ANALYSIS;    MICROSTRUCTURE;    OPERATING TEMPERATURE;    OXIDATION;    PROTECTIVE COATINGS;    REACTION KINETICS;    SILICON DIOXIDE;    STRUCTURAL ANALYSIS;    TEMPERATURE EFFECTS;    THERMOGRAVIMETRY;    WATER VAPOR;    X RAY DIFFRACTION;   

RP-ID  :  GRC-E-DAA-TN71138

美国|英语

来源: NASA Technical Reports Server

【 摘 要 】

Greater gas turbine engine efficiency is a major goal in aeronautics research often pursued through increased engine operating temperatures. However, it is necessary to replace the current hot-stage alloy components with more thermally robust parts, such as promising Silicon-based ceramics and composites. Unfortunately, these materials are still susceptible to the effects of oxidation, water vapor, and (Calcium-Magnesium-Alumino-Silicate) CMAS interaction, among other issues at high temperature. To mitigate these effects, environmental barrier coating (EBC) materials are employed to help control the rate of degradation to the underlying composite. Often, a thermally grown oxide (TGO) layer forms between the EBC and the composite which can act as a point of failure. The current study focuses on the combined effects of water vapor, composite composition, and microstructure in TGO formation on protected and unprotected SiC samples which have been produced under different processing conditions.