Compliant alkali silicate sealing glass for solid oxide fuel cell applications: The effect of protective YSZ coating on electrical stability in dual environment

Recently, compliant sealing glass has been proposed as a potential candidate sealant for solid oxide fuel cell (SOFC) applications. In a previous paper, the thermal stability and chemical compatibility were reported for a compliant alkali-containing silicate glass sealed between anode supported YSZ bi-layer and YSZ-coated stainless steel interconnect. In this paper, we will report the electrical stability of the compliant glass under a DC load and dual environment at 700–800 °C. Apparent electrical resistivity was measured with a 4-ponit method for the glass sealed between two plain SS441 metal coupons or YSZ-coated aluminized substrates. The results showed instability with plain SS441 at 800 °C, but stable behavior of increasing resistivity with time was observed with the YSZ coated SS441. In addition, results of interfacial microstructure analysis with scanning electron microscopy will be correlated with the measured resistivity results. Overall, the YSZ coating demonstrated chemically stability with the alkali-containing compliant silicate sealing glass under electrical field and dual environments.

► Stable resistivity of the compliant glass was observed for the alkali-containing compliant silicate glass with YSZ-coated SS441 substrate.
► No segregation of alkalis (K and Na) was identified along the glass and metal interface.
► Undesirable (unstable) resistivity was observed for glass with plain SS441 at 750 and 800 °C.