Thermal conductivity, phase stability, and oxidation resistance of Y_3Al_5O_(12) (YAG)/Y_2O_3-ZrO_2 (YSZ) thermal-barrier coatings
Abstract
This paper describes a new multilayer TBC that incorporates a 10 μm-thick oxygen barrier layer of yttrium–aluminum garnet (YAG) into a typical YSZ TBC system. The thermal conductivity of as-sprayed YAG/YSZ coatings was reduced due to excessive porosity and amorphous areas in the YAG layer. After long-term heat treatments, the conductivity of the multilayer was unaffected by the presence of YAG. Sintering and recrystallization of the amorphous YAG regions occurred during high-temperature heat treatments. While YAG itself possesses excellent phase stability, its presence also improved the phase stability of zirconia near the YAG/YSZ interface, inhibiting the outward diffusion of yttrium from high-yttria t-ZrO_2 The YAG layer reduced the NiCoCrAlY bond-coat oxidation rate by a factor of three during isothermalfurnace tests conducted at 1200° C.
Additional Information
© 2004 Plenum Publishing Corporation. Received January 13, 2003; revised January 14, 2004. Funding was provided by the U.S. Department of Energy, Federal Energy Technology Center, Cooperative Agreement No. DE-FC21-92MC 29061, under subcontract 96-01-SR047. The thermal conductivity testing was supported by the U.S. DOE, Assistant Secretary of Transportation Technologies, as part of the HTML User Program under contract DE-AC05- 00OR22725, managed by UT-Batelle, LLC. The authors would like to thank Richard Marzec for general assistance in the thermal spray laboratory. Discussions with Dr. Thomas Bernecki were also very useful. The assistance of Dr. Ramesh Subramanian at Siemens-Westinghouse in obtaining superalloy substrates is also appreciated.Additional details
- Alternative title
- Thermal conductivity, phase stability, and oxidation resistance of Y3Al5O12 (YAG)/Y2O3-ZrO2 (YSZ) thermal-barrier coatings
- Eprint ID
- 49380
- Resolver ID
- CaltechAUTHORS:20140908-181321138
- DE-FC21-92MC 29061
- Department of Energy (DOE)
- DE-AC05-00OR22725
- Department of Energy (DOE)
- Created
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2014-09-09Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field