The effect of room temperature and high temperature exposure on the elastic modulus, hardness and fracture toughness of glass ceramic sealants for solid oxide fuel cells

The reliable operation of solid oxide fuel cell stacks (SOFCs) depends strongly on the structural integrity of the sealing material. Indentation testing is used to determine the mechanical properties of glass-ceramic sealants typically used for solid oxide fuel cell stacks, in particular for the evaluation of elastic modulus, hardness and fracture toughness. Different sealing materials partly with reinforcement by metallic or ceramic filler (particles or short fibers) are tested. The materials are tested after the joining procedure and after additional annealing at operation temperatures to test the effect of further crystallization that might take place. Furthermore, the effect of environmentally enhanced slow crack growth at low temperatures in water saturated atmosphere is investigated. Finally, self-healing effects of the glass ceramic materials with and without pre-annealing at typical operation temperatures are considered.