Effects of thermal aging on thermo-mechanical behavior of a glass sealant for solid oxide cell applications

Thermo-mechanical properties of a silicate based glass and its potential use for sealing application in intermediate temperature solid oxide cell (SOC) are presented in this paper. Effects of thermal aging are discussed on structural and microstructural evolution, thermal expansion, viscosity, modulus of elasticity, and high-temperature deformation of the glass. The balance between the viscosity and viscous flowing behavior was explored for the non-aged and aged glasses as it is essential to have a successful sealing for a SOC stack. The results reveal a temperature dependence of Young's modulus in which a transition between a slow softening (elastic) regime and a rapid softening one was observed. Crystallization induced by thermal aging led to higher creep resistance, but lower capability of crack healing when inspected by electron microscopy. However, potential of stress relaxation in the aged material was confirmed by the constitutive mechanical models of viscoelasticity.