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Aerosol Synthesis and Reactivity of Thin Oxide Shell Aluminum Nanoparticles via Fluorocarboxylic Acid Functional Coating




There is currently a need for low oxide content nanoaluminum as a component in high-energy-density fuels. A gas-phase passivation coating of perfluoropentanoic acid on in situ generated bare nanoaluminum accomplished in an aerosol stream and resulting in an air-stable product is demonstrated. Transmission electron microscopy inspection demonstrates a 1–2 nm coating layer, and thermogravimetric analysis reveals an 80% active fuel content, an increase of 17% from untreated product. X-ray photoelectron spectroscopy confirms both the presence of the fluorocarboxylic acid on the aluminum surface and the thinner coating layer compared with the untreated case. A bridge bonding coordination between the carboxylate group and aluminum is indicated via Fourier transform infrared spectroscopy. The coated product demonstrates reduced ignition temperature in thermite combinations for temperature-jump fine wire combustion tests and X-ray photoelectron spectroscopy verifies formation of AlF3 in burned product.