Reactive molecular dynamics simulation of thermal decomposition for nitromethane/nano-aluminum composites
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ORIGINAL PAPER
Reactive molecular dynamics simulation of thermal decomposition for nitromethane/nano-aluminum composites Xin-Ke Wang 1 & Ying Zhao 1 & Feng-Qi Zhao 2 & Si-Yu Xu 2 & Xue-Hai Ju 1 Received: 3 June 2020 / Accepted: 7 October 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The thermal decomposition of pure nitromethane (NM) and NM/nano-aluminum (Al) composites was simulated by reactive molecular dynamics with ReaxFF-lg corrected force field parameters. The initial decomposition pathway of NM molecules in pure NM is C–N bond rupture. However, NM is decomposed early by the initial pathway of N–O bond rupture when it mixes with nano-Al because of the strong attraction of Al to O. The decomposition process of NM/nano-Al can be divided into three stages: adsorption, slow decomposition, and rapid decomposition. The addition of nano-Al particles decreases the energy barrier in decomposition, increases the released energy, and reduces the decomposition temperature of NM. Adding 3% Al to the explosive can make the detonation pressure 3.083% higher than that of pure system. Compared with pure NM, the energy barrier of 16% Al composite is 25.63 kcal/mol lower and the energy released is 22.99 kcal/mol more. There is an optimal amount of Al contents being added to the NM composite by which the largest total numbers of gaseous products (N2, H2O, and CO2) are released. The effect of Al additives on CO2 production is the most obvious. The maximum detonation pressure can be achieved by adding an appropriate amount of nano-Al, which is similar to the experimental results. Keywords ReaxFF-lg . Nano-Al particles . Decomposition pathway . Detonation pressure . Energy release
Introduction Energetic materials (EMs) are a class of compounds or mixtures containing explosive functional groups or oxidants and combustibles that can conduct chemical reactions independently and output energy. EMs have been widely used in military and civil fields because of their excellent detonation performance [1–3]. Among them, nitromethane (NM) is the simple EMs with large specific impulse, low toxicity, and low price. NM has been widely used in the fields of explosives, Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00894-020-04562-7) contains supplementary material, which is available to authorized users. * Xue-Hai Ju [email protected] 1
Key Laboratory of Soft Chemistry and Functional Materials of MOE, School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, People’s Republic of China
2
Science and Technology on Combustion and Explosion Laboratory, Xi’an Modern Chemistry Research Institute, Xi’an 710065, People’s Republic of China
fuels, and propellants because of its advantages [4–6]. So far, there are many researches on pure NM system; these studies mainly focus on the decomposition, structure, and energy of pure NM system [7–11]. Furthermore, with the increase of the expectation for energy, the pure NM usually cannot meet t
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