Effect of fly ash addition on the structure and compressive properties of 4032-fly ash particle composite foams

4032-10vol.% fly ash particle composite foams were processed using stirring technique, followed by direct foaming. Two types of fly ash particles were used; one was microballoons with two different average diameters of 80 and 140 mu m. The other was solid precipitators with an average size of 20 mu m. The structural analysis of the composite foams revealed that the pores were mostly closed-cell and irregular ellipses with nearly the same size in each foam sample. EDXA at fly ash-matrix interface showed excess Mg and O at the interface compared with that at the 4032 matrix alloy. The CTEs of the 4032 foam were higher than those of the composite foams. The compression tests indicated that the 4032 and composite foam stress-strain curves exhibited the behavior of typical plastic foam and the composite foam had higher yield, plateau and plastic stress in comparison to those of the 4032 foam. The composite foams showed a lower strain-hardening exponent when compared with the 4032 foam. As the result of higher strength of the composite foams, the increase in energy absorption of the composite foam sample with fly ash precipitators ranged over two times compared to that of 4032 foam. (C) 2009 Elsevier B.V. All rights reserved.