Research On Vacuum Brazing And Contact Reactive Brazing Of Aluminum Foam

As one kind of rapid developing metal foams, aluminum foam has many characteristics such as light, sound absorption, impact energy absorption and electromagnetic shielding, having enormous potential applications in reinforcing thin walled structural members of satellites, aircrafts, ships and automobiles. In industrial production, the production of large size or complex blanks of aluminum foam is difficult, so it is necessary to research the welding process of aluminum foam. However, the pore structure of aluminum foam seriously reduces its weldability. Nowadays, reports on the welding performance of aluminum foam are less. In this paper, aluminum foam joints were made by vacuum brazing and contact reactive brazing in order to provide necessary experimental information for widespread use of aluminum foam.Butt joints of aluminum foam were made by three different brazing processes including brazing with multilayer filler metal in high vacuum of10-3(Pa) degree, brazing with multilayer filler metal in low vacuum of1(Pa) degree and brazing with monolayer filler metal in high vacuum of10-3(Pa) degree. The macrostructure and microstructure characteristics and bending strength of the joints were investigated and compared. The results indicate that the brazed specimen can achieve satisfactory joint when brazed with multilayer filler metal in high vacuum. The bending strength of the joint is higher than that of the base metal. However, the bending strength of the joint is obviously lower than that of the base metal when brazed with multilayer filler metal in low vacuum, while it is slightly lower when brazed with monolayer filler metal in high vacuum.Under different brazing time, pure aluminum foams were welded by contact reactive brazing with multilayer filler metal in high vacuum of10-3(Pa) degree. The macrostructure and microstructure characteristics and bending strength of the joints were investigated and compared. The specimen, brazed at570℃for15min, failed at the base metal, while the others occurred at the brazing joints. The strength of the joints firstly ascended to the peak point and then decreased with the increase of brazing time. The strength is higher than the strength of aluminum foam under the brazing time of15min.