Stability of SrO–La2O3–Al2O3–SiO2 glass sealants in high-temperature air and steam

Abstract

SrO–La2O3–Al2O3–SiO2 glasses with different SrO content are prepared and their stability in high temperature air and steam are investigated. All glasses are stable during 1000h test at 800°C in air. Nevertheless, the high–SrO glasses (≥40mol%) are devitrified on the surfaces when they are treated at 850–900°C in air or exposed to steam. 29Si magic–angle–spinning nuclear magnetic resonance study reveals weaker connections between [SiO4] tetrahedral units and increased micro–heterogeneity of glass networks with increasing SrO content, which should be responsible to the lower stability of the high–SrO glasses. It indicates that a careful control of SrO content is necessary to develop stable SrO–La2O3–Al2O3–SiO2 glass sealants for solid oxide fuel cells and solid oxide electrolysis cells.