Fabrication and interfacial characterization of aluminum foam sandwich via fluxless soldering with surface abrasion

Abstract

Aluminum foam sandwiches (AFS) with metallic bonding between face sheets and aluminum foam have been produced by the method of fluxless soldering with surface abrasion assisted by vibrations. The effects of vibration modes on mechanical properties and interfacial characterization are analyzed via microstructural observation, tension tests and static three-point bending tests. The average bending strength increases sharply with the increase of vibration frequency and can reach 571% of that of aluminum foam when AFS is made with assisted ultrasonic vibration. Excellent metallic bonding has been informed between face sheets and foam core. The delaminations between face sheets and foam core are not observed and good wetting and spreading process are realized. Particularly, ultrasonic vibration helps to make the microstructure more uniform and reduce the defects of soldering seam. The joining mechanism of Al plate and aluminum foam is explained. A model based on thermodynamic equations is built up to explain interdiffusion process, and the relation between diffusion depth and spreading radius has been discussed. Fluxless soldering with surface abrasion assisted by vibrations has been proven to be suitable for fabricating AFS.