Tailoring oxidation of Al particles morphologically controlled by carbon nanotubes

Aluminum powder is used for energetic materials due to high energy density. Controlling oxidation rate, oxidation temperature, and reaction enthalpy is important parameters prior to practical use. Here, we engineered static and dynamic properties of oxidation of Al particles by mixing CNTs (carbon nanotubes) having high thermal conductivity and large exothermic energy. Morphologies of Al/CNT mixture were engineered by a mechanical pulverization. Among various morphologies of Al/CNT mixture of i) CNTs adhered on the surface of Al particles, ii) CNTs partially embedded onto Al particles, forming an urchin type, and iii) CNTs fully embedded into aggregated Al particles, urchin type Al/CNT revealed the largest exothermic enthalpy at the lower oxidation temperature for both γ-Al2O3 and α-Al2O3 phases. This was attributed to the fast heat transfer into Al particles via partially embedded CNTs. Large exothermic enthalpy as well as the mass of alumina were obtained in oxidation of Al/CNT mixture compared to pure Al particles up to 1000 °C oxidation. The exothermic enthalpy showed strong dependence on the CNT content, increasing to −188 kJ/g at 20 wt% CNT. The engineering ability of thermal properties in Al particles with CNTs opens a new research area for diverse use of solid fuel Al.