等离子喷涂是一种重要的涂层和薄膜制备技术，为在管式固体氧化物燃料电池上沉积陶瓷基连接体提供了重要的方法。然而，传统的等离子喷涂陶瓷涂层具有典型的层状多孔结构，具有大量未结合的界面和透气通道，难以满足防止燃料气体和氧化气体泄漏的微观结构要求。这导致涂层的电导率与烧结块体相比较低，从而导致欧姆电阻增加和输出性能降低。为了改善管式电池等离子喷涂La0.2Sr0.8MnO3-La0.3Sr0.7TiO3（LSM-LST）双层连接体的界面结合和电导率，在LST和LSM涂层内的间隙界面中添加了Co3O4修复添加剂。结果表明，由于液相烧结机理，非结合界面和微裂纹处发生了冶金愈合，在低于块体致密烧结温度的温度下（1200℃）获得了块体状致密组织。界面愈合后稳定涂层的气体泄漏率比未愈合涂层低1个数量级以上。此外，其电导率是未愈合涂层的两倍以上，满足管状电池连接件的微观结构和性能要求。
XRD pattern of LSM and LST powders (a), and the morphologies of (b) LST and (c) LSM powders
XRD patterns of (a) as-sprayed LSM and LST coatings, (b) LSM-Co3O4 and LST-Co3O4 after 450 °C treatment, (c) LSM-Co3O4 and LST-Co3O4 after 1200 °C treatment. (d) The XPS surveys of the LST-Co3O4 and LSM-Co3O4 coatings. High resolution XPS spectra of Co 2p for(e) LST-Co3O4 and (f) LSM-Co3O4 coatings
The cross-sectional SEM images of as-sprayed (a) LST and (b) LSM coatings, (c) LST and (d) LSM coatings after 1200 °C treatment, (e) LST and (f) LSM coatings after infiltration and 450 °C treatment, (g) LST-Co3O4 and (h) LSM-Co3O4 after 1200 °C treatment
The polished cross-sectional SEM images of as-sprayed (a) LST and (b) LSM coatings, (c) LST and (d) LSM coatings after 1200 °C treatment, (e) LST-Co3O4 and (f) LSM-Co3O4 coatings after 1200 °C treatment
The surface morphologies of as-sprayed (a) LST and (b) LSM coatings, (c) LST and (d) LSM coatings after 1200 °C treatment, (e) LST-Co3O4 and (f) LSM-Co3O4 coatings after 1200 °C treatment
(a)The photographs of LST and LSM coating on a porous ceramic tube, (b) the gas leakage rates of the as-sprayed and 1200 °C-treated LSM and LST coatings, (c) the gas leakage rates of the LST-Co3O4 and LSM-Co3O4 coatings and LSM-LST bilayer coating after adding Co3O4
(a)low-magnification cross-sectional SEM image of the LSM-LST bilayer coatings after adding Co3O4 and heat treatment, high-magnification cross-sectional SEM images at the bonding region of (b) the as-sprayed LSM-LST bilayer coating and (c) LSM-LST bilayer coating after adding Co3O4
(a)Lateral conductivity of LSM coatings in the air after different treatments, (b) lateral conductivity of LST coatings in the wet hydrogen after different treatments, and (c) lateral conductivity of LSM-LST bilayer coatings in the corresponding atmosphere after adding Co3O4 and 1200 °C annealed
总而言之，本研究基于界面修复机理，提出了用于管式 SOFC 连接体的等离子喷涂高致密结构 LSM-LST 双层涂层。通过引入 Co3O4 作为界面修复剂，经 1200 °C 热处理后，LSM 和 LST 涂层获得了块状致密结构。修复后的 LSM 和 LST 涂层的气密性比喷涂涂层高出 > 1 个数量级。此外，界面修复的 LSM-Co3O4 涂层在 800 °C 空气中的电导率为 106 S/cm，与高温烧结块体的电导率相当。同样，LST-Co3O4 涂层的电导率是烧结块体的 2 倍以上，在 800 °C 的加湿氢气中为 11.8 S/cm。由界面修复的LSM和LST涂层组成的双层互连系统也表现出高导电性和优异的稳定性，因此可应用于高性能、高稳定性的管状电池互连。
DOI: https://doi.org/10.1007/s11666-024-01859-4
原文链接：https://link.springer.com/article/10.1007/s11666-024-01859-4#Fig6
