Abstract
Higher turbine inlet temperatures may require the use of ceramic matrix composites (CMC) such as SiC/SIC, which require environmental barrier coatings (EBCs) to protect them against the detrimental effect of water vapor. The goal of this project is to determine the maximum bond coating temperature for EBCs for land-based turbines, where the minimum coating lifetime is 25,000 h. If the temperature exceeds the 1414°C melting point of the Si bond coating, then coatings without a bond coating also need to be evaluated. Thus, current Yb2Si2O7EBCs with a Si bond coating and next-generation EBCs without a Si bond coating are being evaluated in laboratory testing using 1-h cycles in air+90%H2O. For this initial work, coatings were deposited on CVD SiC coupons. Reaction kinetics at 1250°, 1300° and 1350°C have been evaluated by measuring the thickness of the thermally grown silica scale after 100-500 h exposures. For comparison, scale growth rates for uncoated SiC and Si specimens in dry and wet environments were included as minimum and maximum values, respectively. Based on a critical scale thickness failure criteria, estimated maximum temperatures were calculated for both EBC systems using this initial data.
| Original language | English |
|---|---|
| Title of host publication | Ceramics and Ceramic Composites; Coal, Biomass, Hydrogen, and Alternative Fuels; Microturbines, Turbochargers, and Small Turbomachines |
| Publisher | American Society of Mechanical Engineers (ASME) |
| ISBN (Electronic) | 9780791884997 |
| DOIs | |
| State | Published - 2021 |
| Event | ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition, GT 2021 - Virtual, Online Duration: Jun 7 2021 → Jun 11 2021 |
Publication series
| Name | Proceedings of the ASME Turbo Expo |
|---|---|
| Volume | 6 |
Conference
| Conference | ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition, GT 2021 |
|---|---|
| City | Virtual, Online |
| Period | 06/7/21 → 06/11/21 |
Funding
The authors would like to thank G. W. Garner, T. M. Lowe, B. Johnston and T. Geer at ORNL for assistance with the experimental work. S. Dryepondt and E. Lara-Curzio provided helpful comments on the manuscript. This research was sponsored by the U.S. Department of Energy, Office of Fossil Energy, Turbine Program (R. Dennis program manager). This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.