Since the development of reactive air brazing the applicability of this technology in demanding devices for energy generation has been examined. Here, ceramic/metal joints have to fulfill challenging demands; i.e. chemical stability in oxidizing and reducing atmospheres, suitable mechanical and thermal properties at elevated temperatures and low porosity. The aging behavior of Ag8Cu, the standard filler metal for reactive air brazing, has been examined before. However, the aging behavior of recently developed fillers has not yet been analyzed thoroughly. In order to improve the understanding about the aging processes and mechanisms the changing of the different areas of brazed 3YSZ/Crofer 22 H joints, e.g. Ag matrix, oxides and interfaces, was analyzed. The growth of the reaction zones during aging was mostly related to the content of oxide forming metals in the filler metal. At least a slight growth could be observed in all samples. The steel was affected by the use of a Ti-containing filler metal. This behavior was further examined by means of differential scanning calorimetry and thermogravimetric analysis. The porosity of several joints increased notably and most samples showed a higher hardness in comparison to that in the asbrazed state. The Cu-free Ag2Fe2Si2Al seems to have the highest aging stability of the analyzed filler metals.
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