Comparison between in-mould and grid-as-mould aluminum foaming process by induction heating

In the last decades, metal foams have been bringing increasing attention because they represent a new category of materials with very intriguing physical and mechanical properties like, for example, high stiffness and low density. These materials have not been studied completely, and many research efforts have been carrying out to investigate new foaming techniques. The present work aimed at evaluating the efficiency of electromagnetic induction as a heating technique of foam precursors for the manufacture of closed-cell aluminum foam specimens by the indirect foaming process known as the powder compact melting technique; a conventional and a flexible mold strategy, the latter using a stainless-steel wire mesh, were employed for the manufacture of parallelepiped specimens. The results outlined the interesting perspectives of this manufacturing method. In detail, they highlighted a significant process repeatability and the beneficial effects of the induction heating method, allowing heating the precursor in very little time and in a safe way compared to conventional heating through a muffle furnace; moreover, they showed the influence of the mould choice both on the processing time, with the synergistic interaction between the flexible mold and the induction system in terms of heat generation, and on the surface geometry of the foamed components, which reflected in their different compression behavior.