Improving the stability of BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3-δ/Crofer 22 H glass-sealed joints in humid oxidizing environments with a Mn-Co spinel coating

Sealing the BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3-δ (BZCYYb) electrolyte to stainless steel interconnect is necessary for proton ceramic fuel cell stack packaging. However, oxidation of the interconnect in the glass-sealed joint presents a significant challenge, especially in humid and oxidizing environments. In this work, a Mn-Co spinel coating was fabricated on Crofer 22 H using microwave heating to extend its service life. The coated Crofer 22 H was successfully sealed to BZCYYb by a SiO₂-TiO₂-K₂O-Na₂O-Al₂O₃-ZnO glass sealant, achieving a sufficient joining. The joint is defect-free and dense, with a shear strength of 20 MPa. Detailed analysis using transmission electron microscopy revealed the underlying sealing mechanism. The Mn-Co spinel coating not only enhances the corrosion resistance of Crofer 22 H but also significantly improves the service life of the joint without compromising strength. The joint remains robust and defect-free after aging in a humid oxidizing atmosphere at 600 °C for 300 h.