Development of the CaO–SrO–ZrO2–B2O3–SiO2 sealing glasses for solid oxide fuel cell applications: structure–property correlation

Abstract

In this study, the structure–property correlation in the CaO–SrO–ZrO₂–B₂O₃–SiO₂ sealing system is systematically investigated. In particular, the effect of ZrO₂ on the structure and chemical compatibility of the glasses is clearly demonstrated. The increases in the glass transition temperature and softening temperature of the glasses indicate that the glass structure is condensed by the ZrO₂ dopant, which is further confirmed by the ¹¹B and ²⁹Si NMR spectra. Furthermore, the addition of ZrO₂ reduces the crystallization tendency of the glasses. The fraction of Cr⁶⁺ in the glass/Cr₂O₃ reaction couple decreases significantly with increasing ZrO₂ content at 700 °C because of the condensed glass structure, whereas the fraction of Cr⁶⁺ increases with increasing ZrO₂ content at 750 and 800 °C. This behavior is related to the increase in residual glass content in the glass–ceramics. Good bondage can be observed at the interfaces between glasses and Crofer 22APU after being held at 800 °C for 500 hours. These results demonstrate the suitability of the Zr-containing glass–ceramics as sealing materials for SOFC applications.