Glass Sealing in Planar SOFC Stacks and Chemical Stability of Seal Interfaces

Abstract

In intermediate temperature planar SOFC stacks, the interconnect, which is typically made from cost-effective oxidation resistant high temperature alloys, is typically sealed to the ceramic PEN (Positive electrode-Electrolyte-Negative electrode) by a sealing glass. To maintain the structural stability and minimize the degradation of stack performance, the sealing glass has to be chemically compatible with the PEN and alloy interconnects. In the present study, the chemical compatibility of a barium-calcium-aluminosilicate (BCAS) based glass-ceramic (specifically developed as a sealant in SOFC stacks) with a number of selected oxidation resistant high temperature alloys, as well as the YSZ electrolyte, was evaluated. This paper reports the results of that study, with a particular focus on Crofer22 APU, a new ferritic stainless steel that was developed specifically for SOFC interconnect applications.