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Glass sealing materials applied in Solid Oxide Fuel Cell (SOFC) are prone to excessive softening and outflow at high temperatures, while cracks tend to form upon cooling. To address these challenges, this study develops mullite fiber reinforced glass sealing materials based on K 2 O–Na 2 O–CaO–BaO–SiO 2 silicate glass, incorporating varying amounts of mullite fibers. The mechanical properties, phase structural transformations, and microstructural changes of these composite sealing materials are thoroughly investigated. The fibers form a network skeletal structure within the sealing material, enhancing the material's strength and high-temperature thermal stability. By incorporating 10% mullite fibers, the G10 sealing material, as compared to pure glass, exhibits a 44% increase in flexural strength and an 85% improvement in maximum strain value. Additionally, G10 boasts a thermal expansion coefficient of 10.25 × 10−6 K−1, demonstrating excellent chemical compatibility with interconnect and achieving tight adhesion at the interface. Most importantly, G10 possesses superior sealing capabilities, maintaining its gastightness even after undergoing 1000 h and 7 thermal cycles without any degradation. • The mullite fiber improves the strength and toughness of the sealing materials. • Mullite fiber form a support structure in the glass and prevent the glass flowing out. • The additional mullite fiber significantly hindered the chromium diffusion at the sealant/interconnect interface. • The leakage rate of the mullite fiber-glass composited sealing material is less than 0.002 sccm cm−1. • The sealant remain gas tightness after 1000 h at 750 °C and 7 thermal cycles. [ABSTRACT FROM AUTHOR]

Sealants based on glass have been widely used in solid oxide fuel cell (SOFC), and have shown considerable potentials due to their low leakage rate. We report a tape of sealant made by adding different contents of diopside into silicate glass, which has a coefficient of thermal expansion (CTE) matching that of adjacent components. Glass-diopside composite sealing material can block the diffusion of chromium from interconnect has been studied. The structure of the 20 wt% diopside doped silicate glass is stable at high temperatures with leakage rates less than 0.004 sccm∙cm−1, and no crystal except for diopside is found in XRD analysis after heating at 750 °C for 100 h. Excellent interface compatibility between the sealant and SUS430 interconnect was proved by SEM at 750 °C for 100 h. The above results prove the possibility of using glass-diopside composite sealing material for SOFC applications. • A composite sealing material is designed by doping diopside into glass. • The CTE of composite sealing material matches that of the adjacent components. • The composite sealing material doped with 20 wt% shows good sealing properties. • The designed composite sealing material has excellent resistance to Cr diffusion. [ABSTRACT FROM AUTHOR]