Understanding and Tuning the Reactivity of Nano-Energetic Materials

Abstract

Mixtures of fuel and oxidizers with particle sizes in the nanometer range have been widely used for energy intensive applications like propellants and explosives. Nano- Al is invariably used as fuel, while a host of metal oxide nanoparticles are used as oxidizers. This article aims at understanding and tuning the reactivity of these nano-energetic materials. The first part of this article discusses the oxidative reactivity of aluminum nanoparticles as measured experimentally using single-particle mass-spectrometer (SPMS) and microscopy and then modeled. Experimental evidence suggests that outward diffusion of aluminum is an important phenomenon in the oxidation of aluminum nanoparticle. Also melting of the aluminum core is necessary for the reaction to take place vigorously. In the second part of the paper we discuss the formation of novel oxidizers. A super-reactive formulation of Al/KMnO4 has been developed which is shown to be orders of magnitude more reactive than the traditional formulations of Al/Fe2O3, Al/MoO3 and Al/CuO. We demonstrate the formation of novel composite oxidizers to tune the reactivity of the Al/Metal oxide system.

Modified Nanoenergetic Composites with Tunable Combustion Characteristics for Propellant Applications

“…Reactivity of nanoenergetic mixtures was determined by monitoring the pressure generated as a function of time during the energetic reaction. The rate of increase in the pressure (pressurization rate) recorded during combustion process is a measure of the reactivity of the material system [13,14,21]. A typical data recorded is shown in Figure 11.…”

Nanoenergetics as pressure generator for nontoxic impact primers: Comparison of Al/Bi2O3, Al/CuO, Al/MoO3 nanothermites and Al/PTFE

“…Nanothermites also open the perspective to fabricate smaller weapon systems or higher lethality weapon. Moreover, compared to conventional explosives, one asset of nanoenergetic materials is the possible adjustment of the energy density, power release and pressure generation by a suitable choice of fuels, oxidizers, material geometries and reactant compaction [3,[14][15][16][17][18][19][20][21][22]. Until recently, very few reports have considered the dynamic pressures developed by the gas expansion during nanothermites reactions [11,[23][24][25].…”

Interfacial Chemistry in Al/CuO Reactive Nanomaterial and Its Role in Exothermic Reaction

“…Reactive nanostructured materials including nanocomposite, based on exothermic thermite reactions, have attracted great interest in the last two decades. Different types of reactive nanocomposites have been synthesized, such as mixed nanopowders, − nanostructured composites, − multilayer nanolaminates, − and dense nanocomposite powders produced by arrested milling. − Whatever the synthesis method and reactive materials types (bimetallics, metal/oxide composites), the main research focus has been to increase the interface area where the exothermic reaction between reactants occurs. For reactant size below 100 nm, the ratio between the bulk reactive reservoir and the interfacial layers is such that the interface zone becomes dominant, thus governing the properties of the overall reactive materials .…”