New double-ceramic-layer thermal barrier coatings based on zirconia–rare earth composite oxides
New double-ceramic-layer thermal barrier coatings based on zirconia–rare earth composite oxides
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DOI：
10.1016/j.jeurceramsoc.2004.11.007
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发表时间：
2006
影响因子：
5.7
通讯作者：
Xueqiang Cao;R. Vaßen;F. Tietz;D. Stoever
中科院分区：
文献类型：
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作者：
Xueqiang Cao;R. Vaßen;F. Tietz;D. Stoever
采用固相反应法合成了一系列La 2 O3-ZrO 2-CeO 2复合氧化物。当Ce/Zr摩尔比≥0.7/0.3时，产物为萤石结构，低于此摩尔比时，产物为La 2 Zr 2 O 7（烧绿石）和La 2 O3-CeO 2（萤石）的混合物。平均而言，CeO 2含量的增加会导致材料的热膨胀系数增加，热导率降低，但La 2（Zr0.7Ce0.3）2 O 7的烧结能力和热导率最低，这可以用声子散射理论解释。利用La2Ce3.25O9.5的热膨胀系数大、La 2 Zr 2 O 7和La 2（Zr0.7Ce0.3）2 O 7的热导率低、烧结性差的特点，制备了双层陶瓷热障涂层。热循环试验表明，这种设计可以大大提高涂层的热循环寿命。由于迄今为止所研究的单一材料都不能满足高温热障涂层的所有要求，因此双陶瓷层涂层可能是热障涂层的一个重要发展方向。
A series of La2O3–ZrO2–CeO2composite oxides were synthesized by solid-state reaction. The final product keeps fluorite structure when the molar ratio Ce/Zr≥0.7/0.3, and below this ratio only mixtures of La2Zr2O7(pyrochlore) and La2O3–CeO2(fluorite) exist. Averagely speaking, the increase of CeO2content gives rise to the increase of thermal expansion coefficient and the reduction of thermal conductivity, but La2(Zr0.7Ce0.3)2O7has the lowest sintering ability and the lowest thermal conductivity which could be explained by the theory of phonon scattering. Based on the large thermal expansion coefficient of La2Ce3.25O9.5, the low thermal conductivities and low sintering abilities of La2Zr2O7and La2(Zr0.7Ce0.3)2O7, double-ceramic-layer thermal barrier coatings were prepared. The thermal cycling tests indicate that such a design can largely improve the thermal cycling lives of the coatings. Since no single material that has been studied so far satisfies all the requirements for high temperature thermal barrier coatings, double-ceramic-layer coating may be an important development direction of thermal barrier coatings.