Crack Mechanism of Al@Al₂O₃ Nanoparticles in Hot Energetic Materials

Abstract

The addition of aluminum (Al) powders to energetic formulations is popular to increase energy, while it gives rise to an issue of how to maximize energy release therein. Cracking Al particles is an efficient way to enhance reactivity and energy release. In the present work, we confirm the crack of Al nanoparticles in hot energetic materials by molecularly simulating the evolution of Al@Al2O3 nanoparticles (ANPs) with imperfect shells and Al slabs covered by perfect Al2O3 layers in a heated widely applied energetic material, 1,3,5-trinitro-1,3,5-triazinane (RDX). The thickening of imperfect shells at an ambient condition by the outward migration of core Al atoms to react with RDX is observed. This thickening is helpful to strengthen the shells and hold melted Al and enhance the internal stress until the crack. While the perfect shells protect the reactions between core Al atoms and RDX, they also induce a crack when heating ANPs at a high temperature. This work is also expected to present an atomic perspective about the structural evolution of other active metallic particles in the wavefront as an extreme in the application.

The combustion-supporting mechanism of fluoropolymers on aluminum particles studied using reactive dynamics simulations

“…To further figure out how the fluoropolymer reacts with the alumina layer, we investigated the evolution of the coordination numbers of sAl atoms. 40 Fig. 9(b)–(d) shows the evolution of iX Al during oxidation.…”

“…To further figure out how the fluoropolymer reacts with the alumina layer, we investigated the evolution of the coordination numbers of sAl atoms. 40 possesses one, two, three, and four nearest-neighbor F atoms, respectively. For the ANP system, the decrease in 1O Al and 2O Al and the increase in 3O Al and 4O Al during the ignition stage imply the further oxidation of the alumina layer.…”

Changes in the state of matter of KCIO4 to improve thermal and combustion properties of Al/MoO3 nanothermite

“…This Intrinsic electric field drives approximately 90% of Al ion mass through [ 48 , 53 ]. The melting-diffusion mechanism refers to the phenomenon where at extremely high heating rates, the volume of the nucleus expands, the pressure increases, the oxide layer splits, and the liquid-phase aluminum disperses into small liquid-phase clusters that fly off at high speeds [ 54 – 56 ]. The combustion test was realized by rapid heating with an electric current, so the ion diffusion mechanism and melting-diffusion mechanism might occur.…”

Adsorption mechanisms of decomposition species of CHON-containing explosives on aluminum surfaces

“…2 The energy release processes of aluminized explosives are complex and multi-staged, involving the ignition and detonation of explosives, 3 and the further oxidation and combustion of Al particles to produce a thermobaric effect. 4,5 Therein, the adsorption of energetic molecules, decomposition species, and oxidants in the air on the Al surface play an important role in enhancing energy release. That is, the adsorption can remarkably accelerate decomposition by reducing the energy barrier, [6][7][8] and initiate the further oxidation and combustion of Al particles to release energy.…”