Low leakage rate of silicate glass modified with Al2O3 for solid oxide fuel cell

Abstract

The gas tightness of glass sealing materials is a big challenge for the solid oxide fuel cell (SOFC) stacks operating at high temperature. Thermal, sintering, crystallization behavior and gas tightness properties of the glass-based with two different Al2O3 contents sealants are evaluated and discussed. The study showed that the sealants avoid cracks at the interface on NiO-YSZ (NiO-yttria stabilized zirconia) and SUS430 stainless steel interconnect substrates. The Al2O3 embedded in the glass matrix as a second phase, and promoted crystallization of K[AlSi3O8] at the early stage. This may because some ultrafine Al2O3 particles whose structure is destroyed by prolonged high temperature treatment according XRD and TEM analysis. Especially, the sealant containing 5 wt% Al2O3 undergoes a thermal cycle and maintains a stable leakage rate below 10−4 sccm∙cm−1 for about 1000 h at 750 °C. The above results prove the possibility of using the Al2O3-doped sealing glass for SOFC stacks.