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Environmental/Thermal Barrier Coatings for Ceramic Matrix Composites: Thermal Tradeoff Studies
| Content Provider | Semantic Scholar |
|---|---|
| Author | Murthy, P. L. Srinivasa Brewer, David N. Shah, Ashwin R. |
| Copyright Year | 2007 |
| Abstract | Summary Recent interest in environmental/thermal barrier coatings (EBC/TBCs) has prompted research to develop life-prediction methodologies for the coating systems of advanced high-temperature ceramic matrix composites (CMCs). Heat-transfer analysis of EBC/TBCs for CMCs is an essential part of the effort. It helps establish the resulting thermal profile through the thickness of the CMC that is protected by the EBC/TBC system. This report documents the results of a one-dimensional analysis of an advanced high-temperature CMC system protected with an EBC/TBC system. The one-dimensional analysis was used for tradeoff studies involving parametric variation of the conductivity; the thickness of the EBC/TBCs, bond coat, and CMC substrate; and the cooling requirements. The insight gained from the results will be used to configure a viable EBC/TBC system for CMC liners that meet the desired hot surface, cold surface, and substrate temperature requirements. Background The development of environmental/thermal barrier coating (EBC/TBC) systems is being pursued under the NASA Ultra-Efficient Engine Technology (UEET) project. The primary objective is to enable the use of ceramic matrix composites (CMCs) in propulsion system components that are subjected to extremely harsh thermal environments. Turbine vanes and combustor liners are examples of such components that need protection from hot combustor gases as well as environmental effects due to moisture, debris, oxygen, and other substances (refs. 1 and 2). A novel concept is under development at the NASA Glenn Research Center for protecting materials against these environmental effects. EBC/TBC material systems developed previously under the High-Speed Civil Transport and Enabling Propulsion Materials programs can perform at material surface temperatures up to 1315 °C. New EBC/TBCs being developed under the NASA UEET project are expected to deliver environmental and thermal protection with assured reliability and durability under very high operating gas temperatures. These coating systems are expected to see surface temperatures around 1480 °C. The bond-coat/substrate interface temperature is required to survive temperatures at least as high as 1315 °C with assured reliability. A pictorial representation of the current state-of-the-art EBC is shown in figure 1. It consists of a CMC substrate, a silicon layer bond coat, a composite layer of mullite and BSAS (barium strontium aluminum silicate), and a pure BSAS layer as the EBC on the top. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070034699.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
