Abstract
Asperities in atmospheric plasma sprayed (APS) CoNiCrAlY bond coatings were observed to rapidly form spinel-type oxides growing into the APS yttria-stabilized zirconia (YSZ) top coating during isothermal exposures. To minimize these transient oxides, bond coatings were either lightly or heavily modified to remove asperities, prior to top coating deposition. After a 100 h isothermal exposure at 1100 °C in dry air, modified regions formed a thin, Al-rich thermally grown oxide (TGO) scale while unmodified regions formed Cr- and Ni-rich transient oxide. However, in 1-h furnace cycle testing (FCT) at 1100 °C, the modified bond coatings showed a reduced average lifetime compared to the specimens with unmodified bond coatings. The benefit of asperities may be to geometrically inhibit crack propagation, but the volume of transient oxide formed may also densify the adjacent YSZ and further inhibit cracking.
| Original language | English |
|---|---|
| Article number | 125042 |
| Journal | Surface and Coatings Technology |
| Volume | 378 |
| DOIs | |
| State | Published - Nov 25 2019 |
Funding
The authors would like to thank B. Zimmerman for technical expertise and J. Williams for helpful comments at CCAM. The authors would also like to thank G. Garner, T. Lowe, and T. Jordan for assistance with the experimental work at ORNL. R. Pillai at ORNL provided helpful comments on the comments on the manuscript. The research at ORNL was sponsored by the U.S. Department of Energy, Office of Fossil Energy, Advanced Turbine Program . Notice: 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. 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 B. Zimmerman for technical expertise and J. Williams for helpful comments at CCAM. The authors would also like to thank G. Garner, T. Lowe, and T. Jordan for assistance with the experimental work at ORNL. R. Pillai at ORNL provided helpful comments on the comments on the manuscript. The research at ORNL was sponsored by the U.S. Department of Energy, Office of Fossil Energy, Advanced Turbine Program.
Keywords
- Atmospheric plasma spray (APS)
- CoNiCrAlY
- Surface engineering
- Surface modification
- Thermal barrier coating (TBC)
- Thermally grown oxide (TGO)