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

Abstract

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 AlF 3 in burned product.