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Kilogram-Scale Production of Air-Stable Nano-Scale Energetic Core-Shell Clusters


OBJECTIVE: Develop scalable processes and technologies for the production of air-stable 5-25 nm scale energetic core-shell clusters comprised of metallic components that undergo inter-metallic or thermite-like reactions. DESCRIPTION: The Air Force is interested in material processing technologies for the production or fabrication of nano-scale core-shell cluster materials with particle diameters<25 nm. There are several possible approaches (including, but not limited to): (i) aerosol condensation methods and (ii) colloidal wet-chemistry based assembly techniques. (i) Aerosol processes for the formation of core-shell nano-clusters involve one of the following methods: the formation of liquid droplets by directing a jet of a source liquid onto a surface or into a stream of gas, by applying high pressures to source liquid and forcing it through a small orifice, or by dropping a source liquid onto a very fast rotating surface. After the formation of the small droplet of, the"core"material, core-shell composite structures could be created through the pyrolysis of the liquid aerosol in the presence of the"shell"material.[1] (ii) Colloidal mechanisms for the formation of core-shell nano-clusters may include the breaking down of larger"bulk"source materials to nano-scale through comminution or by building up atoms and molecules into clusters through aggregate condensation. After formation, shell structures can be formed on spherical colloids by means of controlled adsorption of another species through precipitation, graft polymerization, or through sol-gel techniques.[2] PHASE I: The contractor will develop a scalable process for the creation of air-stable 5-25 nm scale core-shell clusters through both modeling and small scale-testing. Initial tests must demonstrate proof-of-concept (10 grams of material produced, at rates of at least 1 gram per hour) and scalability of production rates. Merit and feasibility must be clearly demonstrated during this phase. PHASE II: Develop, demonstrate, and validate a large scale energetic nano-cluster formation process. The nano-cluster formation process shall produce air-stable 5-25 nm scale energetic core-shell clusters at rates of at least 100 grams per hour. Deliverables are a prototype of the process, a demonstration, experimental data of the production and cluster formation process, a model incorporating the production and cluster formation data, and an analysis of the resulting material. PHASE III: Military Application: Air-stable 5-25 nm scale energetic core-shell cluster based material suitable for use in munitions with production rates of at least 10 kg per hour. Commercial Application: Improvement of energy output of jet fuels. REFERENCES: 1. Prakash, A., A.V. McCormick, and M.R. Zachariah, Tuning the Reactivity of Energetic by Creation of a Core-Shell. Nano Letters, 2005. 5(7): p. 1357-1360. 2. Caruso, F., Colloids and Colloid Assemblies: Synthesis, Modification, Organization and Utilization of Colloid Particles2004: John Wiley & Sons. 621.
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