Abstract

Carlos G. Levi
University of California Santa Barbara

February 12, 2007
3:30- 4:30pm
MEC Rm. 341

"Considerations in the Design of Alternate Thermal Barrier Oxides"

Zirconia partially stabilized with 7±1wt%Y2O3 (7YSZ) has been the standard material for thermal barrier coatings (TBCs) since their insertion into gas turbine engines.  The demands for increased engine performance and fuel flexibility translate into higher temperatures and more aggressive operating environments for TBCs, motivating the search for alternate materials preferably retaining ZrO2 as the base oxide.  Because a key element in the durability of current TBCs is their non-transformable tetragonal (t') structure, which is metastable, one must tread carefully in the design space to achieve desired targets in functionality such as lower thermal conductivity or increased corrosion resistance, while maintaining adequate toughness, phase stability, compatibility with the underlying thermally grown oxide (TGO) and morphological stability of the strain-tolerant microstructure.  These challenges will be discussed in light of current work on alternate TBCs driven by desired improvements in resistance to erosion, cyclic life and attack by molten deposits.

USA Acknowledgments: The presentation includes contributions from R.M. Leckie, F.M. Pitek, T.A. Schaedler (former graduate students) and S. Krämer (post-doc), and benefits from collaborations with various industrial and academic groups.  The research was sponsored by the Office of Naval Research (N00014-99-1-0471 and MURI/N00014-00-1-0438) and by the National Science Foundation (DMR-0605700 and DMR-0080021).

About the speaker:  C.G. Levi received a Ph.D. in Metallurgical Engineering from the University of Illinois at Urbana-Champaign in 1981 and has been in the faculty at UCSB since 1984, where he is Professor of Materials and Mechanical Engineering. His research interests are on the fundamental understanding of microstructure evolution during synthesis and processing of inorganic materials, and the application of this understanding to the design and synthesis of improved coatings, thin films, composites and monolithic systems.  Current areas of work include thermal and environmental barrier coatings for advanced gas turbines, refractory alloys and ultra high temperature materials for hypersonic flight, oxide-oxide composites with matrix-enabled damage tolerance, and the study of metastable phenomena during the synthesis of functional oxides.  Additional information is available at http://www.materials.ucsb.edu/~levic/levi.html.

 

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