Theoretical Study On The Interaction Of FOX-7 With Solid Interface

Compared with energetic materials, Metallized energetic materials have much outstanding performance. They are widely used in propellants due to the properties of evident after-burning effects, long-lasting of energy releasing, high temperature and high energy in detonation, and so on. In this thesis, Al, Mg, Cu, Al-Mg alloy, Al-Cu alloy, Fe₂O₃, CuO and FOX-7 were selected, Systematical studies were carried out by the quantum mechanics methods to investigate the adsorption and decomposition of FOX-7 molecule on the surface mentioned above.1. The relaxations of Al（110）、Mg（001）、Cu（110）、Al₁2Mg₁7（110）、Al₂Cu（110）、Fe₂O₃（110） and CuO（110） were investigated using the density functional theory calculations. The geometrical structures, bonding properties and electronic conformations of the surfaces are different from the bulk materials. From the analysis of the surface electron density, the value of the surface energy is determined by the redistributes of the surface electron density.2. The adsorption of the FOX-7 molecule on the Al, Mg, Cu, Al₁2Mg₁7, Al₂Gu, Fe₂O₃ and CuO surface was investigated by the adsorption energy（Eabs） and the optimization of adsorption configuration. The adsorption brings about the decomposition of the FOX-7 and the common products are C₂N₂H₄NO₂NO+O, C₂N₂H₄NO₂N+2O, C₂N₂H₄NONO+2O or C₂N₂H₃NO₂NO₂H. The radical kinds are adsorbed on the surface. The largest adsorption energy is-1441.524kJ/mol（the adsorption of FOX-7 molecule on Mg surface）. These surfaces are easily oxidized by the dissociation of the O and N atoms from the nitro group to form strong covalent bonds like Al-O and Al-N. For the adsorption of the FOX-7 molecule on the Fe₂O₃（110）and CuO（110） surface, the bond lengths of Fe-O and Cu-O change greatly. Fe₂O₃ and CuO become activated as a result of the adsorption of the FOX-7.3. From the analysis of Mulliken charge and density of states（DOS）, the mechanism of electron transfer was studied. The maximum charge transfer is 3.484e（the adsorption of FOX-7 molecule on Al₁2Mg₁7 surface） from the surface to the FOX-7 molecule. With the increase of dissociated bonds of FOX-7, the charges of surface atoms increase markedly, while the charges of O and N atoms decrease sharply. In the FOX-7 decomposition, the density of states peak values of O and N atomic have undergone great change, which illustrates that a strong chemical interaction occurs between the systems.4. The activation energy of the reaction path and the decomposition mechanism of FOX-7 molecule was determined by the transition-state theory. We can conclude that the barrier energy of FOX-7 dissociation is as small as-19.18kcal/mol while the barrier energies for the other configurations are much larger.