Double Rare-Earth Oxides Co-doped Strontium Zirconate as a New Thermal Barrier Coating Material
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JTTEE5 22:104–109 DOI: 10.1007/s11666-012-9854-y 1059-9630/$19.00 ASM International
Double Rare-Earth Oxides Co-doped Strontium Zirconate as a New Thermal Barrier Coating Material Wen Ma, Dongxing Wang, Hongying Dong, Wenshan Lun, Weiyan He, and Xuebin Zheng (Submitted June 11, 2012; in revised form September 6, 2012) Y2O3 and Yb2O3 co-doped strontium zirconate with chemistry of Sr(Zr0.9Y0.05Yb0.05)O2.95 (SZYY) was synthesized and had a minor second phase of Yb2O3. The SZYY showed good phase stability not only from room temperature to 1400 C but also at high temperature of 1450 C for a long period, analyzed by thermogravimetry-differential scanning calorimetry and x-ray diffraction, respectively. The coefficients of thermal expansion (CTEs) of the sintered bulk SZYY were recorded by a high-temperature dilatometer and revealed a positive influence on phase transitions of SrZrO3 by co-doping with Y2O3 and Yb2O3. The thermal conductivities of SZYY were at least ~30% lower in contrast to that of SrZrO3 and 8YSZ in the whole tested temperature range. Good chemical compatibility was observed for SZYY with 8YSZ or Al2O3 powders after a 24 h heat treatment at 1250 C. The phase stability and the microstructure evolution of the as-sprayed SZYY coating during annealing at 1400 C were also investigated.
Keywords
perovskites, TBC, thermal conductivity, thermal expansion
1. Introduction Ceramic thermal barrier coatings (TBCs) offer the potential to significantly improve efficiencies of aero engines as well as stationary gas turbines for power generation (Ref 1-3). To date, 7-8 wt.% Y2O3-stabilized ZrO2 (YSZ) has been considered as a standard TBC material due to its low thermal conductivity, phase stability at temperatures below 1200 C and chemical inertness in combustion atmospheres (Ref 4). However, YSZ cannot This article is an invited paper selected from presentations at the 2012 International Thermal Spray Conference and has been expanded from the original presentation. It is simultaneously published in Thermal Spray 2012: Proceedings of the International Thermal Spray Conference, Air, Land, Water, and the Human Body: Thermal Spray Science and Applications, Houston, Texas, USA, May 21-24, 2012, Basil R. Marple, Arvind Agarwal, Laura Filofteia-Toma, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Andre´ McDonald, Ed., ASM International, Materials Park, OH, 2012. Wen Ma, Dongxing Wang, and Wenshan Lun, School of Materials Science and Engineering, Inner Mongolia University of Technology, Hohhot, Inner Mongolia 010051, PeopleÕs Republic of China; Hongying Dong and Weiyan He, School of Chemical Engineering, Inner Mongolia University of Technology, Hohhot, Inner Mongolia 010051, PeopleÕs Republic of China; and Xuebin Zheng, Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences, Shanghai 200050, PeopleÕs Republic of China. Contact e-mail: [email protected].
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be operated long-term at ~1200 C because of phase transitions and accelerated sintering (Ref 5-
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