Brazing of ceramic-to-ceramic and ceramic-to-metal joints in air

Reactive air brazing (RAB) is an emerging technology for the production of ceramic-to-ceramic and ceramic-to-metal joints. In this study, RAB was investigated with respect to the potential applications for solid oxide fuel cells (SOFCs) as one example of use. It was found that alumina could be well brazed by RAB with AgCu and AgCuTi brazes. Both braze composition and brazing temperature influenced significantly the wetting behavior and their mechanism of wetting. AgCu and AgCuTi braze alloys could also be used to produce brazed joints with the SOFC materials ceramic yttria stabilized zirconia and steel X1CrTiLa22. However, CuO reacts with the steel, forming a brittle oxide layer on the steel surface, which is undesirable for SOFC applications. The first trials with Ag0.5Al showed a promising solution.