New Aluminum Syntactic Foam: Synthesis and Mechanical Characterization.

Metal matrix syntactic foams (MMSF) are advanced cellular materials constituted by a system of a minimum of two phases, in which a dispersion of hollow particles is embedded by a continuous metal matrix. The incorporation of porous fillers favors the development of low-density materials with exceptional behavior for damping vibrations, impacts, and blast effects, shielding acoustic, thermal, and electromagnetic energies. There are three main techniques to produce them: infiltration casting technique (ICT), stir casting technique (SCT), and powder metallurgy technique (P/M). The first two techniques are used for embedding filler into lower melting point metallic matrices than fillers, in contrast to P/M. The present study demonstrates the feasibility of producing MMSF with components of similar melting points by ICT. The fillers were synthesized in-situ with aluminum and a natural foaming agent from wastes of Spanish white marble quarries. These novel aluminum syntactic foams (ASF) were mechanically characterized following the ISO-13314 and exhibited a porosity, plateau stress, and energy absorption capacity of 41%, 37.65 MPa, 8.62 MJ/m (at 35% of densification), respectively. These properties are slightly superior to equal porosity LECA ASF, making these novel ASF suitable for the same applications as LECA-ASF.