Hydration-induced plasma surface modification of aluminum nanoparticles for power generation in oxygen deficient environments

Abstract

An approach to increase the energy release rate from aluminum (Al) combustion is to modify the alumina (Al2O3) passivation shell surrounding the Al fuel core. One approach uses atmospheric plasma treatment to physically reduce the Al2O3 shell thickness while simultaneously exposing the defected surface to water vapor to promote surface hydration. Combining water-vapor with an atmospheric helium dielectric barrier discharge (DBD) plasma yields a thinner Al2O3 shell with double the surface hydration compared to as-received aluminum nanoparticles (nAl). Non-equilibrium combustion studies on plasma-treated nAl particles demonstrate increased energy release rates owing to the thinned shell and reduced diffusion barrier. Adding hydration further provides more oxidizer species in molecular scale proximity to the core such that the thinned and hydrated shell increased the initial pressurization rate by 50 % compared to as-received nAl. The results introduce a method to modify the native oxide surface and a strategy to control energy release rates from metal particle combustion.