Low-density expanded perlite-aluminium syntactic foam

This paper addresses an innovative syntactic foam (SF) formed by counter-gravity infiltration of a packed bed of low-cost expanded perlite (EP) particles with molten A356 aluminium. The uniform distribution of EP particles in foams causes an even density throughout the height. Due to the low density (similar to 0.18 g/cm(3)) of EP, the average density of these foams is only 1.05 g/cm(3) which is considerably lower than most studied SFs. Owing to the high porosity of the filler material (similar to 94%), the total porosity of the new foam reaches 61%. Microstructural observations reveal no sign of damage or unintended EP particle infiltration. EP shows a good wettability whilst essentially no reaction occurs at the EP-metal interface. Under compression, EP/A356 syntactic foam shows stress-strain curves consisting of elastic, plateau and densification regions. On account of its consistent plateau stress (average value 30.8 MPa), large densification strain (almost 60%), and high energy absorption efficiency (88%) EP/A356 syntactic foam is an effective energy absorber. (c) 2014 Elsevier B.V. All rights reserved.