Abstract
The addition of an air plasma sprayed (APS) “flash” layer on top of a high velocity oxygen fuel (HVOF) bond coating has been shown to extend the lifetime of thermal barrier coatings. A series of furnace cycle tests (FCTs) has been conducted at 1100 °C in air + 10% H2O to study the benefit of flash coatings on rod and disk alloy 247 specimens and provide a better mechanistic understanding of their benefit. Flash coatings of NiCoCrAlY and NiCoCrAlYHfSi both improved the FCT lifetime of rod specimens tested in 100-h cycles and disk specimens tested in 1-h cycles. In 1-h cycles, the NiCoCrAlY flash coating significantly outperformed an HVOF-only NiCoCrAlYHfSi bond coating and a NiCoCrAlYHfSi flash coating. Both flash coatings increased the bond coating roughness compared to HVOF. During exposure, the flash layer formed an intermixed alumina-metal layer that appeared to inhibit crack formation. Using a time series of observations, the lower Y + Hf content in the Y-only flash coating appeared to reduce Al consumption. The HVOF layer acted as a source of Al for the adjacent mixed zone. A second series of specimens included a fully APS bond coating where oxide had penetrated through the entire coating to the substrate after only 100, 1-h cycles and lifetime was similar to an HVOF-only bond coating. The inner HVOF layer with the outer APS flash coating prevented this complete penetration from occurring.
| Original language | English |
|---|---|
| Title of host publication | Superalloys 2020 - Proceedings of the 14th International Symposium on Superalloys |
| Editors | Sammy Tin, Mark Hardy, Justin Clews, Jonathan Cormier, Qiang Feng, John Marcin, Chris O'Brien, Akane Suzuki |
| Publisher | Springer Science and Business Media Deutschland GmbH |
| Pages | 739-746 |
| Number of pages | 8 |
| ISBN (Print) | 9783030518332 |
| DOIs | |
| State | Published - 2020 |
| Event | 14th International Symposium on Superalloys, Superalloys 2021 - Seven Springs, United States Duration: Sep 12 2021 → Sep 16 2021 |
Publication series
| Name | Minerals, Metals and Materials Series |
|---|---|
| ISSN (Print) | 2367-1181 |
| ISSN (Electronic) | 2367-1696 |
Conference
| Conference | 14th International Symposium on Superalloys, Superalloys 2021 |
|---|---|
| Country/Territory | United States |
| City | Seven Springs |
| Period | 09/12/21 → 09/16/21 |
Funding
Notice: This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the US Department of Energy. The US Government retains and the publisher, by accepting the article for publication, acknowledges that the US 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 US 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). Acknowledgements G. Garner, T. Lowe, T. Jordan, V. Cox assisted with the experimental work at ORNL. This research was sponsored by the US Department of Energy, Office of Fossil Energy, Advanced Turbine Program (R. Dennis program manager and P. Burke project monitor). G. Garner, T. Lowe, T. Jordan, V. Cox assisted with the experimental work at ORNL. This research was sponsored by the US Department of Energy, Office of Fossil Energy, Advanced Turbine Program (R. Dennis program manager and P. Burke project monitor).
Keywords
- APS flash coating
- Furnace cycle testing
- Thermal barrier coatings