Wetting Properties and Interface Reaction Mechanism of Ag-Cu Brazes on Dual-phase Membrane Ceramic

A reactive air brazing Ag-Cu O alloy was evaluated for brazing dual phase oxygen membrane Ce sub(0.8) Gd sub(0.2) O sub(2-[delta])-NdBaCo sub(2) O sub(5+[delta])(CGO-NBCO). Contact angle tests were observed between Ag-Cu brazes and CGO-NBCO in air and the interfacial microstructures of the used samples were evaluated by SEM. The results indicate that the wetting angle decreases from 35[degrees] to 20[degrees] with the content of Cu increased from 6.6mol% to 15.8mol%. It is found that there are copper oxide-enriched zones formed in the junction of the alloy and substrate. The wettability between Ag-Cu O alloy and oxygen membrane CGO-NBCO is improved due to the interfacial reaction between Cu oxides in braze and the surface layers of CGO-NBCO substrates to form compounds of Ba-Cu-O, Co-Cu-O and Nd-Ce-Cu-O oxides. The new formed interface reaction layers promote the wettability of the rest braze.