Abstract
Thermally grown oxide scales that form beneath ZrO2 top coats play an important role in determining the performance of thermal barrier coatings. Numerous factors, including the composition of both the alloy substrate and the bond coat, affect adhesion of the α-Al2O3 scale. Three areas of focus in the formation of an 'ideal', adherent scale encompass: (1) migration of Al and other elements in the metal substrate, (2) segregation of elements to the metal-scale interface and the scale grain boundaries, and (3) generation of stresses in the scale. Examples of the effects of reactive elements, Pt, indigenous S, and reaction temperature on scale adhesion are discussed.
Original language | English |
---|---|
Pages (from-to) | 201-211 |
Number of pages | 11 |
Journal | Materials Science and Engineering: A |
Volume | 245 |
Issue number | 2 |
DOIs | |
State | Published - May 1 1998 |
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.