Synthesis and characterization of hollow glass sphere containing aluminum syntactic foam by spark plasma sintering and hot pressing

Abstract

The effect of sintering process on the microstructure and the mechanical properties of aluminum syntactic foam were investigated in this study. Two different sintering processes of spark plasma sintering and hot pressing were used. Glass hollow spheres with a size of 50-80 µm was used to fabricate the foams having various volume fractions of the spheres in the range of 10-30%. Microstructural analysis revealed that the glass hollow spheres were uniformly distributed in the aluminum matrix, both in the spark plasma sintered and hot pressed ones. As the volume fraction of the spheres increased from 10 to 30%, the density, micro-hardness and compressive strength of the foams were decreased. In comparison to the foams fabricated by hot pressing method, the spark plasma sintered foams had slightly lower density and mechanical strength. In nanoindentation study, it was found that the aluminum matrix in the foam prepared by the spark plasma sintering process had lower strength than foam prepared by the hot pressing process. This is likely because of shorter sintering time used in the spark plasma sintering process than the hot pressing.