Effects of Mo Interlayer on Suppressing Cracks in Al2O3/Kovar Brazed Joint

In order to avoid the formation of cracks at Al2O3/Kovar joint, Mo was coated on the Kovar surface by Magnetron sputtering method. Meantime, Ti-Cu-Ni active filler metal was employed to braze Al2O3 and Kovar. The interfacial microstructure and element distribution were analyzed by SEM and EDS methods. It can be found that the cracks were avoided when the Mo layer was 14.2 mu m in thickness. Meanwhile, the results also show that Mo interlayer decreased the reaction rate between Fe element from the base material and Ti element from the filler metal. That is, fewer FexTiy intermetallic compounds were formed at the interface, and therefore the formation of cracks at the reaction interface were suppressed.