Progress in the study of glass-based systems as sealants for proton ceramic electrolysis cell assembly

This study compares a commercial boron-based glass and its composite, obtained by adding 5 wt% 3YSZ, with a silica-based glass as sealants for joining AISI 441 ferritic stainless-steel interconnectors to BZCY622/NiOBZCY622 protonic ceramic half-cells. The boron-based glass and its composite exhibited lower glass transition temperatures (500◦C–600 ◦C), making them well-suited for the operating range of PCECs. The composite approach enabled tuning of the viscous flow behavior, softening temperature, and coefficient of thermal expansion (CTE) while also enhancing the thermal stability. SEM-EDX characterization of samples joined with the composite system confirmed no significant structural evolution after aging for 500 h at 600 ◦C in an air-steam mixture (70 %–30 % vol.). Both the boron-based glass and its composite effectively relaxed stresses induced by CTE mismatch between the joined layers and by the chemical expansion of the electrolyte, demonstrating excellent thermal stability under severe cycling conditions in an air-steam mixture (70 %–30 % vol.).