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

Abstract

Aluminum (Al) possesses high combustion enthalpy and is thus extensively used as the fuel additive in explosives to form aluminized explosives with excellent energy performance. In the energy release process of aluminized explosives, the adsorption of Al surfaces plays an important role in catalyzing the explosive decomposition and triggering the oxidation of themselves. However, it still remains elusive owing to the multiplicity of adsorbed substances. Herein, the adsorption mechanism of decomposition species of CHON-containing explosives on Al surfaces is studied synoptically by combining reactive molecular dynamics simulations with density functional theory calculations. The results indicate that the Al surface structure and the activity of adsorbed molecules both have an impact on adsorption. The cluster surface generally outperforms the slab one in adsorptivity due to the lower coordination number of Al atoms. Meanwhile, the more active adsorbed molecules lead to chemisorption or even dissociative adsorption, beneficial to the subsequent Al oxidation. Besides, electrons will transfer from the Al surface to the adsorbed molecules as chemisorption occurs; while the density of states of the Al surface and molecules are altered, especially for carbon oxides with significant electronic delocalization. This work is expected to deepen insights into the energy release of aluminized explosives and help provide a proposal for enhancing energy release efficiency.