Abstract
The adhesion of alumina scale to the metal substrate Zr-doped β-NiAl is studied to determine the effects of the alloy substrate and bond coat on the adhesion. Three general factors contributed to the ideal scale formation and adhesion: no major redistribution of alloying elements within the metal substrate; segregation of Zr to the metal-scale interface and the scale grain boundaries; and ability to tolerate stresses generated in the scale. Several potential strategies are suggested to form more adherent alumina scales in practical thermal barrier coating systems: add more Al to aluminide coatings; investigate bond coat microstructures or phases; identify the elements detrimental to scale adhesion; and add reactive elements to PtAl coatings.
| Original language | English |
|---|---|
| Pages (from-to) | 109-125 |
| Number of pages | 17 |
| Journal | NASA Conference Publication |
| Issue number | 207429 |
| State | Published - May 1998 |
| Event | Proceedings of the 1997 Thermal Barrier Coating Workshop - Cincinnati, OH, USA Duration: May 19 1997 → May 21 1997 |
Funding
The authors would like to thank P.F. Tortorelli, J.R. DiStefano, J.A. Haynes, P.F. Becher and J.H. DeVan at ORNL for their comments. T. Geer and J.W.Jones at ORNL assisted with the metallography. B.A. Nagaraj at GEAE assisted in providing coatings and substrates. NASA Lewis Research Center provided NiAl substrates (J.D. Whittenberger and J. Doychak), coatings (W.J. Brindley) and useful comments (J.L. Smialek). This research was sponsored by the US Department of Energy, Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Industrial Technologies, as part of the Advanced Turbine Systems Program (ORNL program manager, M.A. Karnitz) and by the Division of Materials Sciences under contract DE-AC05-96OR22464 with Lockheed Martin Energy Research Corporation.