Structure, crystallization, and performances of alkaline‐earth boroaluminosilicate sealing glasses for SOFCs

Abstract

We study the structure, crystallization, and performances of the sealing glasses with the composition (mol.%) of 12Al2O3·8B2O3·40SiO2·40RO (R = Mg, Ca, Sr) for solid oxide fuel cells (SOFCs) before and after isothermal treatment at 700°C, which is within the operation temperature range (600‐800°C) of SOFCs. The crystallization behavior has been investigated by differential scanning calorimetry and X‐ray diffraction under both dynamic and isothermal conditions. The structural evolution is probed using the Raman and nuclear magnetic resonance spectroscopies. The performances of the sealing glasses are characterized in terms of the coefficient of thermal expansion, the crystallization‐induced stress at glass–steel interface. We find that strong crystallization occurs at the operation temperature (700°C) far below the crystallization onset temperature measured by DSC. The structure origin of this anomalous crystallization is discussed in terms of structural heterogeneity of the three studied glasses. We determine the residual stress at the interface between the Ca‐containing glass and the steel after isothermal treatment at 700°C for 48 h, but this stress does not lead to falling off the glass layer from the steel. This indicates that this glass is a good candidate to be applied in SOFCs.

Effect of particle size distribution on crystallization behavior of glass‐based seals in reversible solid oxide cells

“…A wide range of desired properties in RSOC can be achieved with glass and glass-ceramic seals by tailoring compositions. [18][19][20][21][22][23][24] Physical and chemical properties and thermal stability have to be satisfied simultaneously in glass seal during RSOC operation. The physical properties mainly include glass transition temperature (T g ), softening temperature (T s ), crystallization peak temperature (T p ), and CTE.…”

“…Various rigid seals have been investigated in RSOC application. A wide range of desired properties in RSOC can be achieved with glass and glass–ceramic seals by tailoring compositions 18–24 . Physical and chemical properties and thermal stability have to be satisfied simultaneously in glass seal during RSOC operation.…”