THERMAL REACTIVITY OF Al/Fe CORE-SHELL NANOCOMPOSITES

To improve the thermal reactivity of aluminum micro-particles, Al/Fe nanocomposites with core-shell structure were prepared by a displacement method, in which Al micro-particles were coated by Fe nanoparticles. The reactivity of Al before and after coating was examined via thermal analysis. Moreover, to demonstrate the significant role of surface coating a mixture consisting of micro-Al and nanoFe was also tested. Two oxidizers (O-2 and CuO) were employed to react with the fuels. The parameters derived from thermogravimetric (TG), differential scanning calorimetric (DSC), and differential thermogravimetric (DTG) curves of each sample were compared. It was obvious that the reaction involving Al/Fe exhibited the highest integrated heat (in DSC), the highest weight increase (in TG), and the largest reaction rate (in DTG). Only Al/Fe-O-2 and Al/Fe-CuO exhibited a distinct low-temperature reaction adjacent to the Al melting point, which may be significant in their ignition at high heating rates. Moreover, Al/Fe fueled systems manifested the lowest apparent activation energy comparing with systems using [Al+Fe] and raw Al as the fuels. All these results affirmed augmentation in thermal reactivity arising from surface coating with nano-Fe.