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

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.