Reactive brazing of ceria to an ODS ferritic stainless steel

Abstract

This research study shows that a ceria ceramic can be bonded to an ODS ferritic stainless steel (MA956) by reactive brazing using a Ag68-Cu27.5-Ti4.5 interlayer. The ability to join these materials provides an alternative to the current ceramic interconnects used in the development of solid oxide fuel cells. Initial results show that the ceramic-metal bonds survived the bonding process irrespective of the degree of porosity within the ceria ceramic. Metallographic analyses indicate that a reaction zone formed along the ceria/braze interface, which was not only titanium rich, but also consisted of a mixture of copper oxides. When the ceramic-metal bonds were exposed to high bonding temperatures or when subjected to thermal cycling at 700°C, this reaction layer increased in thickness and had a detrimental affect on the mechanical strength of the final joints.