Chemical interactions of BaO-containing borosilicate glass-ceramic sealant with AISI 441 for SOEC at 750 °C and 850 °C

This study investigates the chemical interactions between a BaO-containing glass-ceramic and AISI 441 stainless steel in air. Two distinct reaction regimes are identified, depending on the local oxygen partial pressure. Near the air/steel/glass-ceramic triple-phase boundary (TPB), the high oxygen partial pressure promotes the formation of barium chromates (BaCrO 4 ). At 750 °C, these compounds predominantly form on the glass surface, whereas at 850 °C they also develop at the steel/glass interface. This reaction results in pronounced chromium depletion in the vicinity of the TPB. Localized catastrophic oxidation of the steel is observed at 850 °C. This behavior is attributed primarily to local changes in the BaO concentration within the glass, which are believed to induce liquid-phase formation. Away from the TPBs, under low oxygen partial pressure, chromium borides and a continuous BaCrSi 2 O 6+x interfacial layer are formed. The role of these phases on SOECs lifespans deserves further investigation.