Sealing arrangement for high-temperature fuel cell stack

Abstract

Disclosed is a sealing assembly for metal components, wherein the sealing assembly has an electrical insulating effect, and wherein the sealing assembly comprises a ceramic layer and a base brazing material disposed thereon, to which germanium is added. The addition of germanium advantageously ranges from 0.1 to 5.0 mol %, and preferably between 0.5 and 2.5 mol %. A particular embodiment provides for the use of a brazing material which additionally comprises silicon in the range of >0 to 2.5 mol %, and preferably between 0.1 and 0.9 mol %. Furthermore, a brazing material having a further addition of 10 to 40% by volume of AlTiO, and preferably between 20 and 30% by volume of AlTiO, has proven to be particularly suited for the sealing assembly. The use of the special brazing material composition inside the sealing assembly generally results in reproducibly tight and insulating joints having the following properties: a) escape of brazing material is prevented and running of brazing material is reduced, b) the porosity of the brazing material (primarily individual pores or narrow pore lines) is markedly reduced, c) the brazed joints have sufficient electrical resistance, and d) the brazed joints are generally sufficiently gas-tight (leakage rate during He leakage test <10mbar*1*s).