Thermite reactions of Al/Cu core-shell nanocomposites with WO3

The Al/Cu core-shell nanocomposites are fabricated via a facile displacement method and characterized by scanning electron microscopy (SEM) and energy dispersion spectrometry (EDS). In comparison with the thermite reactions of bulk Al powders with WO3, the thermite reactions of Al/Cu core-shell nanocomposites with WO3 as a function of the equivalence ratio of Al to WO3 (Φ) and reaction environment are investigated by differential scanning calorimetry (DSC) and dealt with in terms of reaction performance of thermite including onset and peak temperatures, maximum reaction rate (Qmax) and reaction heat (ΔHr) based on DSC data. The results indicate that the reactivity of Al/Cu core-shell nanocomposites with WO3 is higher than that of bulk Al powders but depends strongly on the equivalence ratio, which is optimal when the fuel in the thermites is slightly rich, i.e. Φ = 1.2. It is significant that in air, ΔHr of WO3 and core-shell Al/Cu (Φ = 1.2) is higher than that of WO3 and bulk Al by 49%. In addition, it is also observed that the solid phase reaction 2Al(s) + WO3(s) = Al2O3(s) + W(s) may be irritated prior to Al melting when heating Al/Cu–WO3 in argon, which is confirmed by DSC and X-ray diffractometry (XRD). Finally, the reasons of improving the thermal performance of thermites have been discussed.