Interface stability between bare, MnCo spinel coated AISI 441 stainless steel and a diopside-based glass-ceramic sealant

This study is focused on a diopside-based glass-ceramic sealant for solid oxide fuel cells and its compatibility with AISI 441 stainless steel interconnect. The morphological and chemical stability with both bare and MnCo spinel coated AISI 441 steel, after 3500 h exposure at 800 °C in air, is reviewed and discussed. Post-mortem samples are morphologically and chemically analysed by SEM-EDS. Reaction products at the glass-ceramic/bare AISI 441 interface, resulting from the reaction of Mg from the sealant and Cr and Mn from the steel, are detected, without affecting negatively the integrity of the joints. In the case of MnCo spinel coated AISI 441, interactions between the glass-ceramic and the outer part of the MnCo spinel coating, along with crystallization of oxides rich in Si and Mg, are detected, but still no corrosion phenomena are present. The glass-ceramic is found to be compatible with both bare and coated AISI 441.