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Thermal conductivity, phase stability, and oxidation resistance of Y_3Al_5O_(12) (YAG)/Y_2O_3-ZrO_2 (YSZ) thermal-barrier coatings

Su, Y. J. and Trice, R. W. and Faber, K. T. and Wang, H. and Porter, W. D. (2004) Thermal conductivity, phase stability, and oxidation resistance of Y_3Al_5O_(12) (YAG)/Y_2O_3-ZrO_2 (YSZ) thermal-barrier coatings. Oxidation of Metals, 61 (3-4). pp. 253-271. ISSN 0030-770X.

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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.

Item Type:Article
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Faber, K. T.0000-0001-6585-2536
Alternate Title:Thermal conductivity, phase stability, and oxidation resistance of Y3Al5O12 (YAG)/Y2O3-ZrO2 (YSZ) thermal-barrier coatings
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.
Funding AgencyGrant Number
Department of Energy (DOE)DE-FC21-92MC 29061
Department of Energy (DOE)DE-AC05-00OR22725
Subject Keywords:thermal barrier coating; conductivity; X-ray diffraction; garnet; zirconia
Issue or Number:3-4
Record Number:CaltechAUTHORS:20140908-181321138
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:49380
Deposited By: George Porter
Deposited On:09 Sep 2014 14:53
Last Modified:03 Mar 2020 13:01

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