Controlling the redox reaction at the interface between sealing glasses and Cr-containing interconnect: Effect of competitive reaction

• The competitive reaction reduces the glass/metal interfacial reaction.
• The reaction also results in a stable Mn–Cr oxide scale at the interface.
• The Mn–Cr oxide scale acts as diffusion barrier at the glass/metal interface.

In this paper, MnO2 is added to CaO–SrO–B2O3–SiO2 sealing system to control the redox glass/metal interfacial reaction in Solid Oxide Fuel Cells. The effect of MnO2 dopant on the valance states of Mn ions in glasses, the glass structure and glass/metal interfacial reaction is systematically investigated. The quenched glasses contain Mn2+ ion only; whereas, the Mn3+ content in glasses, held at 600 °C for 9 h, increases with increasing MnO2 dopant. The good bondage can be observed at the interfaces between Crofer 22APU and glass containing 6 mol % MnO2, held at 700 °C for 500 h. The competitive reaction reduces the redox chromate formation by consuming the oxygen at the glass/metal interface. In addition, the competitive reaction results in the formation of a continuous Mn–Cr oxide scale at the glass/metal interface, which is helpful for reducing the further diffusion of Cr from metallic interconnect to glass.