Densification and enhancement of the grain boundary conductivity of gadolinium-doped barium cerate by ultra fast flash grain welding
Densification and enhancement of the grain boundary conductivity of gadolinium-doped barium cerate by ultra fast flash grain welding
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DOI：
10.1016/j.jeurceramsoc.2012.01.032
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发表时间：
2012-08
影响因子：
5.7
通讯作者：
R. Muccillo;E. Muccillo;M. Kleitz
中科院分区：
文献类型：
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作者：
R. Muccillo;E. Muccillo;M. Kleitz
掺杂CeO_3是一种很有前途的中温燃料电池质子导体固体电解质。然而，在合理的温度下很难将其烧成高密度。此外，它在中温下表现出高的晶界电阻率。对压实试件进行闪光颗粒焊，焊接温度为910℃，短时施加40V，1000 Hz的交流极化。在该频率下，产生的电流流过晶界，通过局部焦耳加热促进焊接。阻抗谱分析表明，晶界电阻率有较大幅度的下降。扫描电子显微镜观察抛光和蚀刻表面显示高度烧结区。还尝试了将闪光晶粒焊与常规烧结相结合。
Doped barium cerate is a promising solid electrolyte for intermediate temperature fuel cells as a protonic conductor. However, it is difficult to sinter it to high density at a reasonable temperature. Moreover, it presents a high grain boundary resistivity at intermediate temperatures. Flash grain welding was applied to compacted samples, starting from a temperature of 910°C and applying, for a short time, an ac electric polarization of 40V, 1000Hz. At that frequency, the resulting current flows through the grain boundaries promoting a welding via a local Joule heating. A large decrease of the grain boundary resistivity was observed by impedance spectroscopy. Scanning electron microscopy observations of polished and etched surfaces revealed highly sintered regions. Attempts were also made to combine flash grain welding with conventional sintering.