Abstract
Failure of electron-beam physical vapor deposition (EB-PVD) thermal barrier coatings (TBCs) with aluminide bond coats is strongly influenced by bond coat oxidation behavior. This study investigated oxide (Al2O3) formation during EB-PVD processing of TBCs with (Ni,Pt)Al bond coats. The effects of substrate composition, coating impurities and bond-coat grit-blasting on the oxide phases, residual stress and microstructure were evaluated. As-deposited, high-purity commercial bond coats contained high concentrations of sulfur and other impurities at their surfaces. Numerous small voids formed at the oxide-metal interface when as-deposited bond coats were oxidized during EB-PVD processing. Grit-blasting of (Ni,Pt)Al had a significant impact, since the formation of α-Al2O3 during EB-PVD processing was significantly enhanced and voids did not form beneath the scale. Preliminary cyclic oxidation testing suggested an influence of superalloy sulfur content on TBC durability.
| Original language | English |
|---|---|
| Pages (from-to) | 140-146 |
| Number of pages | 7 |
| Journal | Surface and Coatings Technology |
| Volume | 146-147 |
| DOIs | |
| State | Published - Sep 2001 |
Funding
The authors thank B. Pachman, B. Warnes and K. Murphy of Howmet Research Corporation for superalloy casting and coating fabrication. Thanks are extended to T. Geer for metallography, L.W. Walker for microprobe analysis, M.P. Brady and P.F. Tortorelli, all of ORNL, for helpful reviews. Research sponsored by the US Department of Energy, Office of Power Technologies, Advanced Turbine Systems Program under Contract DE-AC05-00OR22725 with UT-Battelle, LLC.
| Funders | Funder number |
|---|---|
| Office of Power Technologies | DE-AC05-00OR22725 |
| U.S. Department of Energy |
Keywords
- Aluminide bond coat
- Electron-beam physical vapor deposition (EB-PVD)
- Thermal b arrier coating (TBC)