Phase structure and thermophysical properties of co-doped La2Zr2O7 ceramics for thermal barrier coatings
Phase structure and thermophysical properties of co-doped La2Zr2O7 ceramics for thermal barrier coatings
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DOI：
10.1016/j.ceramint.2011.12.077
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发表时间：
2012-07
影响因子：
5.2
通讯作者：
J. Xiang;Shuhai Chen;Jihua Huang;Huanshui Zhang;Xingke Zhao
中科院分区：
文献类型：
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作者：
J. Xiang;Shuhai Chen;Jihua Huang;Huanshui Zhang;Xingke Zhao
la2zr2o7熔点高，导热系数低，热膨胀率较高，适合用作高温热障涂层。采用固相法合成了La2Zr2O7、（La0.7Yb0.3）2(Zr0.7Ce0.3) 2o7和（La0.2Yb0.8）2(Zr0.7Ce0.3) 2o7陶瓷。研究了共掺杂对la2zr2o7相结构和热物理性能的影响。通过x射线衍射鉴定了这两种陶瓷的相结构，结果表明：la2zr2o7陶瓷具有焦绿石结构，而共掺杂陶瓷（La0.7Yb0.3）2(Zr0.7Ce0.3) 2o7和（La0.2Yb0.8）2(Zr0.7Ce0.3) 2o7表现为缺陷萤石结构，其主要由离子半径比r(Aav.3+)/r（Bav.4+）决定。从室温到1200℃的热膨胀系数和导热系数测试表明，共掺杂陶瓷（La0.7Yb0.3）2(Zr0.7Ce0.3) 2o7和（La0.2Yb0.8）2(Zr0.7Ce0.3) 2o7比la2zrr0.8具有更高的热膨胀系数和更低的导热系数，并且由于yb2o3含量的增加，（La0.2Yb0.8）2(Zr0.7Ce0.3) 2o7表现出比（La0.7Yb0.3）2(Zr0.7Ce0.3) 2o7更优异的热物理性能。
La2Zr2O7has high melting point, low thermal conductivity and relatively high thermal expansion which make it suitable for application as high-temperature thermal barrier coatings. Ceramics including La2Zr2O7, (La0.7Yb0.3)2(Zr0.7Ce0.3)2O7and (La0.2Yb0.8)2(Zr0.7Ce0.3)2O7were synthesized by solid state reaction. The effects of co-doping on the phase structure and thermophysical properties of La2Zr2O7were investigated. The phase structures of these ceramics were identified by X-ray diffraction, showing that the La2Zr2O7ceramic has a pyrochlore structure while the co-doped ceramics (La0.7Yb0.3)2(Zr0.7Ce0.3)2O7and the (La0.2Yb0.8)2(Zr0.7Ce0.3)2O7exhibit a defect fluorite structure, which is mainly determined by ionic radius ratio r(Aav.3+)/r(Bav.4+). The measurements for thermal expansion coefficient and thermal conductivity of these ceramics from ambient temperature to 1200°C show that the co-doped ceramics (La0.7Yb0.3)2(Zr0.7Ce0.3)2O7and (La0.2Yb0.8)2(Zr0.7Ce0.3)2O7have a larger thermal expansion coefficient and a lower thermal conductivity than La2Zr2O7, and the (La0.2Yb0.8)2(Zr0.7Ce0.3)2O7shows the more excellent thermophysical properties than (La0.7Yb0.3)2(Zr0.7Ce0.3)2O7due to the increase of Yb2O3content.