A Preliminary Study on Adhesion on Steel Cylinder Filled with Aluminum Foam

In the last decades, metallic foams found commercial and industrial interests, thanks to their physical properties combined with good mechanical characteristics. Metal foam structures are very light and they can be used to reduce the weight of machinery without compromising the mechanical behavior. In this work, a study of the direct junction of metal foam with metal massive components was carried out. Aluminium foams were manufactured starting from commercial foamable precursors. First of all, attention was paid to the repeatability of foaming process. Then, a direct connection between the foamed samples and the steel shell elements was pursued. The materials that seemed to facilitate the formation of an intermetallic layer were studied and the geometry of the steel mould and the most useful way to place the precursor in the steel mould and then in the furnace were considered. To evaluate the produced aluminum foam, morphological and mechanical characterizations were done. Results showed that, keeping constant the contour conditions, it was possible to control the process and a first result, in terms of interaction between foam and mould, was obtained using an X210Cr12 steel as mould material. The SEM observation revealed the presence of an intermetallic phase. 1. Introduction Metal foams are cellular materials generally obtained by the dispersion of a gas in a solid material. There are different methods to produce metal matrix cellular solid and they are classified according to the starting state of the metal processed. Metal foams can be manufactured starting by solid, liquid, and vapor metal of a solution of metal ions. In this work, foamed samples were realized by the so-called “powder metallurgy” method; it was developed at the Fraunhofer Institute in Bremen (Germany) [1] and it leads to foamed structures because it involves the decomposition of particles that release gas in semisolid. Foamable precursors are thermally treated in an oven, so that the foaming process occurs. Foamable powder compacts can be produced indoor; thus, the process begins with the mixing of metal powders with a blowing agent, titanium hydride (TiH2) typically. Then, the mix is compacted to gain a dense, semifinished product called “precursor.” The compaction of the mixed powders must be done by a technique that ensures the blowing agent is embedded into the metal matrix without any notable residual open porosity. In this work, commercially available precursors of AlSi0.6Mg1 and AlSi10 with TiH2 as blowing agent were used; thus, the production of the metal foamable compacts