Diffusion bonding in fabrication of aluminum foam sandwich panels

This work describes a detailed investigation on fabrication of mild steel-Al foam core sandwich panels (AFS) by vacuum free diffusion bonding method. The foamable AlMg1/SiCp-based precursor was prepared by powder metallurgy method. In order to prevent the surface oxidation and to facilitate the bonding process, the mild steel sheets were aluminized by hot dipping technique. A series of experiments were completed at various processing parameters for preliminarily evaluating the joint quality and the foamability of the precursor. The distribution characteristics of the SiCp particles at the bond line was particularly investigated and discussed. The results have shown that a pre-bonding of the steel/precursor was required for the formation of high quality joint between cover sheets and aluminum foam core. Besides, both the fabrication of aluminum foam core and the bonding of the aluminum foam to the cover sheets were achieved simultaneously. An approach for fabricating AFS panels with steel as cover sheet was establish, and an simple model of the diffusion bonding mechanism for the formation of metallurgical bonding interface was proposed. The obtained results may have particularly importance on applications of AFS panels that need firmly bonded joints.