Low-Thermal-Conductivity Rare-Earth Zirconates for Potential Thermal-Barrier-Coating Applications |
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| Authors: | Jie Wu,Xuezheng Wei,Nitin P. Padture,Paul G. Klemens,Maurice Gell,Eugenio Garcí a,Pilar Miranzo,Maria I. Osendi |
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| Affiliation: | Department of Metallurgy and Materials Engineering, Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269–3136;Department of Physics, Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269–3136;Instituto de Cerámica y Vidrio, CSIC, Cantoblanco, 28049 Madrid, Spain |
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| Abstract: | Rare-earth zirconates have been identified as a class of low-thermal-conductivity ceramics for possible use in thermal barrier coatings (TBCs) for gas-turbine engine applications. To document and compare the thermal conductivities of important rare-earth zirconates, we have measured the thermal conductivities of the following hot-pressed ceramics: (i) Gd2Zr2O7 (pyrochlore phase), (ii) Gd2Zr2O7 (fluorite phase), (iii) Gd2.58Zr1.57O7 (fluorite phase), (iv) Nd2Zr2O7 (pyrochlore phase), and (v) Sm2Zr2O7 (pyrochlore phase). We have also measured the thermal conductivity of pressureless-sintered 7 wt% yttria-stabilized zirconia (7YSZ)—the commonly used composition in current TBCs. All rare-earth zirconates investigated here showed nearly identical thermal conductivities, all of which were ∼30% lower than the thermal conductivity of 7YSZ in the temperature range 25°–700°C. This finding is discussed qualitatively with reference to thermal-conductivity theory. |
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| Keywords: | barriers coatings thermal conductivity zirconate |
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