SiO2-CaO-B2O3-Al2O3微晶玻璃在平板式ITSOFC中密封性能的研究

平板式中温固体氧化物燃料电池(ITSOFC)的密封材料在工作温度下,与其接触的电池材料应具备以下特性:(1)气密性;(2)尺寸稳定性;(3)热匹配性;(4)化学稳定性;(5)绝缘性.采用SiO₂-CaO-B₂O₃-Al₂O₃系统微晶玻璃制备出一种适用于850℃的密封材料.该材料在850℃保证一定尺寸的前提下,能够与8YSZ电解质和Ni-Cr双极板紧密黏附,热膨胀系数8.9×10^-6)/℃和8YSZ接近,电导率约为10^-8S/cm有良好的电绝缘性能,在O₂和H₂气氛下保温100h没有气体泄漏,且密封后的黏附界面边界分明,元素扩散层厚度<10μm.实验证明该材料适用于ITSOFC 850℃密封.

SiO2-CaO-B2O3-Al2O3 Glass Ceramics as Sealant for Planar Intermediate Temperature Solid Oxide Fuel Cells

The sealant materials for planar intermediate temperature solid oxide fuel cells (ITSOFC) are required for the sealing of the different components to prevent from leakage. Besides the gas tightness, the sealants should show good wetting behavior, matching thermal expansion, chemical stability, dimension stability and insulation. It was investigated that a glass-ceramic based on the SiO₂-CaO-B₂O₃-Al₂O₃ system as sealant material applied for ITSOFC operated at 850℃. After heat treatment at 850℃ for 2h, the glass ceramic maintained its shape, bonded with 8YSZ electrolyte and Ni-Cr bipolar producing a good gas-tight seal, and its thermal expansion coefficient of 8.9×10^-6/℃ was close to 8YSZ. After 100h, no decrease in pressure caused by H₂ or O₂ leaking was observed, its micrograph showed a good connection with clear interface and the thickness of the diffusive layer of elements was less than 5～10μm. This study shows the glass ceramic sealant is suitable for ITSOFC.