Novel alkaline earth silicate sealing glass for SOFC: Part II. Sealing and interfacial microstructure

This is the second part of a study of a novel Sr–Ca–Ni–Y–B silicate sealing glass for solid oxide fuel cells (SOFC). Part I of the study addresses the effect of NiO on glass forming, thermal, and mechanical properties, and is presented in the preceding paper. In this paper (part II), candidate composite glass with 10 vol.% NiO was tested for sealing standard coupons of Ni/YSZ anode-supported YSZ electrolyte bilayer and metallic interconnect Crofer22APU at various temperatures. Samples sealed at the highest temperature (1050 °C) showed hermetic seal after fully reduction and 10 thermal cycles. The interfacial microstructure characterization showed no distinct reactions at the interfaces of glass/YSZ or glass/metal, though some segregation of Ni was found along the glass/metal interface. Possible reactions were discussed. Overall the composite glass with 10 vol.% NiO appeared to be a good candidate for SOFC sealing.