Fabrication of Fe/Al2O3 composite foam via combination of combustion synthesis and spark plasma sintering techniques

Iron–alumina composite foam was prepared through combination of combustion synthesis (CS) and spark plasma sintering (SPS) techniques. Al, Fe2O3 and Fe powders were used as starting materials. Samples containing 5–20 wt.% (Al + Fe2O3) powders and balanced content Fe powder were sintered by SPS apparatus. The microstructure observation and phase identification of the synthesized samples were conducted by using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Applying pulsed electric current to the powder led to the formation of Al2O3 by occurrence of a highly exothermic reaction between Al and Fe2O3 according to: XFe + 2Al + Fe2O3 = Al2O3 + (X + 2) Fe. It was found that the time duration for obtaining the maximum combustion temperature was increased by increasing the X content. In addition, porosity increased with decreasing X content in the starting powder mixture at a constant sintering time. The porosity of Fe/Al2O3 composite products for X = 80, 85, 90 and 95 were measured 18%, 44%, 52% and 60%, respectively.

► Fe–Al2O3 composite foam was fabricated in one step by SHS–SPS processes in less than 80 s, starting from Fe, Fe2O3 and Al powders.
► The porosity increased with increasing Fe2O3 + Al content in specimens at a constant sintering time.
► The measured porosity for samples containing 95, 90, 85, and 80 wt.% of Fe and Al + Fe2O3 as remaining were 18%, 44%, 52% and 60% respectively.