A novel method to evaluate the suitability of glass sealant–alloy combinations under SOFC stack conditions

A novel test method has been developed to evaluate the suitability of combinations of sealing materials and alloys under simulated SOFC stack conditions. This method is based on test samples of two metallic sheets, joined together with a glass or glass–ceramic sealant. The outer side of the sample is exposed to ambient atmosphere, whereas the inner side can be exposed to different gas compositions. The whole set-up is placed in a furnace. Optionally, an external voltage can be applied across the sheets. The background of the experimental design was the development of a methodology to investigate interaction phenomena between steel alloys and glass ceramic sealants under controlled conditions. Although exposure and oxidation experiments under atmospheric conditions did not show any indication of detrimental effects, corrosion was observed in actual stack experiments. The experimental set-up was thus designed in order to study the influence of single parameters on the interaction of alloy and sealant. With this method the governing influences in simulated SOFC operation can be identified. Obviously, the presence of a dual hydrogen–air atmosphere induces enhanced corrosion in certain material combinations. The experiments presented here allow a systematic study of the materials in question and a rapid characterisation.