Glass-ceramic sealants for solid oxide fuel cells: Part I. Physical properties

Abstract

A family of sealant materials has been developed for use in the solid oxide fuel cell (SOFC) and in other applications in the temperature range of 800-1000 ± C. These materials are based on glasses and glass-ceramics in the SrO-La 2 O 3 -Al 2 O 3 -B 2 O 3 -SiO 2 system. The coefficients of thermal expansion (CTE) for these materials are in the range of 8-13 3 10 26 ͞ ± C, a good match with those of the SOFC components. These sealant materials bond well with the ceramics of the SOFC and, more importantly, form bonds that can be thermally cycled without failure. At the fuel cell operating temperature, the sealants have viscosities in the range of 10 4 -10 6 Pa-s, which allow them to tolerate a CTE mismatch of about 20% among the bonded substrates. The gas tightness of a sample seal was demonstrated in a simple zirconia-based oxygen concentration cell.

Materiais cerâmicos para células a combustível

“…Estes materiais devem possuir temperatura de transição vítrea mais baixa possível para evitar tensões devidas às diferenças de valores do coeficiente de expansão térmica [105]. Entretanto, a viscosidade destes materiais na temperatura de operação deve ser maior que 10 3 Pa.s para permanecerem estanques [105].…”

“…Estes materiais devem possuir temperatura de transição vítrea mais baixa possível para evitar tensões devidas às diferenças de valores do coeficiente de expansão térmica [105]. Entretanto, a viscosidade destes materiais na temperatura de operação deve ser maior que 10 3 Pa.s para permanecerem estanques [105]. Os materiais comumente citados são à base de vidros sodacálcia, de outros silicatos alcalinos, de silicatos alcalinos terrosos e de borosilicatos alcalinos [105].…”

“…Entretanto, a viscosidade destes materiais na temperatura de operação deve ser maior que 10 3 Pa.s para permanecerem estanques [105]. Os materiais comumente citados são à base de vidros sodacálcia, de outros silicatos alcalinos, de silicatos alcalinos terrosos e de borosilicatos alcalinos [105].…”

Effects of lanthanum-to-calcium ratio on the thermal and crystalline properties of BaO–Al₂O₃–B₂O₃–SiO₂ based glass sealants for solid oxide fuel cells

“…700900°C). In our previous work, 43) we reported that the GC9 glass and GC9 glass-ceramic with La/Ca ratio of 0.833 exhibited an excellent matching with the typical stainless steel interconnect and PEN plate at temperature below 650°C. Figure 2 shows the typical thermal expansion curves of GC9 glass with various La/Ca ratios in the range of 0 to 1.4.…”

“…Sohn et al 19) found that the 42) have studied the Sr/Ca ratios on the structure, crystallization behavior and properties of diopside-based glass, and they reported that the tendency towards crystallization was retarded with increasing Sr/Ca ratio. Ley et al 43) found that the viscosity is sensitive to the B 2 O 3 /SiO 2 ratio in the SrOLa 2 Notably, a suitable glass-ceramic sealant for SOFC must offer a good wetting and mechanical strength to keep adhesion and gas tightness during operating at elevated temperatures. A novel barium-aluminum-borosilicate system glass named GC9, which was developed by the Institute of Nuclear Energy Research (INER) as a high-temperature seals for SOFC sealing.…”