Abstract
Environmental barrier coatings (EBCs) will be needed to protect SiC-based ceramic matrix composite components for the next generation of high-efficiency industrial gas turbines (IGTs). The IGT application will require ≥25 kh lifetimes, and little data are available on EBC failure mechanisms, particularly at ≥1300°C. Initial 1-h furnace cycle testing at 1350°C in 90 vol% H2O/10 vol% air was conducted ≥1000 cycles on thermally sprayed ytterbium disilicate (YbDS) coatings with and without an Si bond coating. By ≥1000 h, both EBCs formed thick, highly cracked, and fully crystalline cristobalite scales. Comparison of thermally grown oxide (TGO) microstructure and kinetics to isothermal rates of Si and SiC steam oxidation indicated a departure from slow-growing parabolic growth to more rapid rates of silica formation. Possible mechanisms and implications for this acceleration are discussed.
Original language | English |
---|---|
Pages (from-to) | 2754-2763 |
Number of pages | 10 |
Journal | Journal of the American Ceramic Society |
Volume | 105 |
Issue number | 4 |
DOIs | |
State | Published - Apr 2022 |
Funding
♣This manuscript has been authored by UT‐Battelle, LLC, under contract number DE‐AC0500OR22725 with the US Department of Energy. The publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid‐up, irrevocable, world‐wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for the United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe‐ public‐ access‐ plan). The authors would like to thank T. Geer and V. Vox for the metallography and G. Garner, P. Stack, B. Johnson, and J. Wade for experimental efforts. Valuable insight was provided by both J. Keiser and M. Ridley during writing stages. This work was sponsored by the Office of Fossil Energy, Department of Energy, Advanced Turbine Program managed by Richard Dennis.