Thermal radiation and cycling properties of (Ca,Fe) or (Sr,Mn) co-doped La2Ce2O7 coatings |
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Affiliation: | 1. State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, No. 122, Luoshi Road, Wuhan, 430070, P. R. China;2. School of Materials Science and Engineering, Wuhan University of Technology, No. 122, Luoshi Road, Wuhan, 430070, P. R. China;3. Department of Physics and Astronomy, University of Missouri-Kansas City, Kansas City, MO, 64110, United States |
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Abstract: | La2Ce2O7 with low thermal conductivity as a potential candidate of thermal barrier coatings (TBCs) was co-doped with (Ca, Fe) or (Sr, Mn) in order to further improve its thermal radiation at high temperatures. The microstructure, chemical composition, infrared emission properties (reflection and absorption properties) and thermal cycling lifetime of the coatings were respectively investigated. The results revealed that La2-xCaxCe2-xFexO7+δ and La2-xSrxCe2-xMnxO7+δ coatings had defected fluorite structure and their infrared emittances were much higher than that of the parent La2Ce2O7. The superior infrared emission could be ascribed to the enhancement of the intrinsic absorption (electron transition absorption), free-carrier absorption and impurity absorption as well as lattice vibration absorption. However, the thermal cycling lifetime of La2Ce2O7 coatings presented a reduction after the (Ca, Fe) or (Sr, Mn) substitution, primarily due to the decrease in the fracture toughness and the increase in the thermal conductivity. |
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Keywords: | Thermal radiation Infrared emittance Co-doping Thermal barrier coatings (TBCs) |
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