Composition Effects on Aluminide Oxidation Performance: Objectives for Improved Bond Coats
Formerly, the role of metallic coatings on Ni-base superalloys was simply to limit environmental attack of the underlying substrate. However, a new paradigm has been established for metallic coatings adapted as bond coats for thermal barrier coatings. It is no longer sufficient for the coating to just minimize the corrosion rate. The metallic coating must also form a slow-growing external Al{sub 2}O{sub 3} layer beneath the overlying low thermal conductivity ceramic top coat. This thermally grown oxide or scale must have near-perfect adhesion in order to limit spallation of the top coat, thereby achieving a long coating lifetime. While oxidation is not the only concern in complex thermal barrier coating systems, it is, however, a primary factor in developing the next generation of bond coats. Therefore, a set of compositional guidelines for coatings is proposed in order to maximize oxidation performance. These criteria are based on test results of cast alloy compositions to quantify an d understand possible improvements as a basis for further investigations using coatings made by chemical vapor deposited (CVD). Experimental work includes furnace cycle testing and in-depth characterization of the alumina scale, including transmission electron microscopy (TEM).
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 788646
- Report Number(s):
- P01-111729; TRN: US200203%%201
- Resource Relation:
- Conference: 9th International Symposium on Superalloys 2000, Champion, PA (US), 09/17/2000--09/21/2000; Other Information: PBD: 6 Sep 2001
- Country of Publication:
- United States
- Language:
- English
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Compositional Effects on Aluminide Oxidation Performance: Objectives for Improved Bond Coats