Accelerated degradation of sealant/interconnect joint in solid oxide cell stacks

[Display omitted] •New insight is presented into the electrical stability of seal/interconnect joints.•Resistivity and microstructural changes were studied under accelerated conditions.•Voltage, current inversing mode, and temperature were stressors for degradation.•Different microstructural aspects were observed at negative/positive interfaces.•Cr and Mn accumulation at anode and Si accumulation at cathode was observed. The electrical and microstructural stability of a model glass sealant sandwiched between two SS430 interconnects was investigated in terms of designed acceleration stress (AST) tests for 500 h in the air. Under applying different stressors, including DC voltage (0–35 V), inverse voltage cycles (3 and 4 cycles), and temperature (700–800 °C), morphological changes of anodically/cathodically polarized interfaces were studied. With 0.7 V and 750 °C, the specimen showed a stable electrical resistivity with well-bonded interfaces. Under higher voltages, a resistivity decay was observed with accelerated interfacial corrosion and delamination at the anode and roughening and losing contacts due to Si accumulation at the cathode side. With cyclic polarization, lower degradation in resistivity and less interfacial deterioration were observed. Aging at higher temperature was accompanied by a slight decrement in the resistivity.