Phase structure and thermophysical properties of co-doped La2Zr2O7 ceramics for thermal barrier coatings
- 作者：Jianying Xiang ; Shuhai Chen ; Jihua Huang ; jihuahuang47@sina.com ; Hua Zhang ; Xingke Zhao
- 关键词：Thermal conductivity ; Thermal expansion ; Ceramic ; Co-doping
- 刊名：Ceramics International
- 出版年：2012
- 期刊代码：13_02728842
- 类别：ms
- 出版时间：July, 2012
- 卷：38
- 期：5
- 页码：3607-3612
- 文件大小：515 K
摘要
La2Zr2O7 has 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)2O7 and (La0.2Yb0.8)2(Zr0.7Ce0.3)2O7 were synthesized by solid state reaction. The effects of co-doping on the phase structure and thermophysical properties of La2Zr2O7 were investigated. The phase structures of these ceramics were identified by X-ray diffraction, showing that the La2Zr2O7 ceramic has a pyrochlore structure while the co-doped ceramics (La0.7Yb0.3)2(Zr0.7Ce0.3)2O7 and the (La0.2Yb0.8)2(Zr0.7Ce0.3)2O7 exhibit 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 掳C show that the co-doped ceramics (La0.7Yb0.3)2(Zr0.7Ce0.3)2O7 and (La0.2Yb0.8)2(Zr0.7Ce0.3)2O7 have a larger thermal expansion coefficient and a lower thermal conductivity than La2Zr2O7, and the (La0.2Yb0.8)2(Zr0.7Ce0.3)2O7 shows the more excellent thermophysical properties than (La0.7Yb0.3)2(Zr0.7Ce0.3)2O7 due to the increase of Yb2O3 content.