Mechanical behavior of silver reinforced glass-ceramic sealants for solid oxide fuel cells

The structural integrity of the sealant is crucial for a reliable operation of solid oxide fuel cell stacks and systems. In this respect, fracture properties and elevated temperature deformation are aspects which need to be assessed, particularly for partially crystallized glass-ceramic sealants that might suffer from instability issues at operation relevant temperatures due to viscoelastic deformation of the residual glass phase. Bending tests are carried out at room temperature and typical stack operation temperatures (700 and 800 degrees C) on an Ag reinforced sealant in a head-to-head specimen geometry in the as-sintered and annealed state, yielding average fracture stresses and creep data. The results reveal a decrease of the fracture stress at elevated temperatures, where this effect appears to be less pronounced for the annealed material. Complementary microstructural analyses aid the understanding of the mechanical behavior and in particular the influence of silver particles. Creep tests reveal a remarkably stronger creep resistance of this material compared to a YSZ reinforced glass-ceramic sealant variation. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.