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Reactive Molecular Dynamic Simulation of Thermal Decomposition for Nano-Aluminized Explosives

Abstract

Aluminized explosives have important applications in civil constructions and military armaments, but their thermal decomposition mechanisms are not well characterized. Here, the thermal decomposition of TNT, RDX, HMX and CL-20 on Al nanoparticles is examined by reactive dynamic simulations using a newly parameterized reactive force field with low gradient correction (ReaxFF-lg). The partially passivated Al nanoparticles were constructed and mixed with TNT, RDX, HMX and CL-20 crystals and then the mixed systems are heated to high temperature in which the explosives are fully decomposed. The simulation results show that the aluminized explosives undergo three main steps of thermal decomposition, which were denoted as "adsorption period" (0-20 ps), "diffusion period" (20-80 ps) and "formation period" (80-210 ps). These stages in sequence are the chemical adsorption between Al and surrounding explosive molecules (R-NO2-Al bonding), the decomposition of the explosives and the diffusion of O atoms into the Al nanoparticles, and the formation of the final products. In the first stage the Al nanoparticle removes the decomposition reaction barriers of RDX (1.90 kJ/g), HMX (1.95 kJ/g) and CL-20 (1.18 kJ/g), respectively, and decreases the decomposition reaction barrier of TNT from 2.99 to 0.29 kJ/g. Comparing with the crystalline RDX, HMX and CL-20, the energy releases are increased by 4.73-4.96 kJ/g in the second stage. The numbers of produced H2O are increased by 25.27%-27.81% and the numbers of CO2 are decreased by 47.73%-68.01% in the third stage. These three stages are confirmed further by the evolutive diagram of the structure and temperature distribution for the CL-20/Al system. The onset temperatures (To) of generating H2O for all the aluminized explosives decrease, while that of generating CO2 for aluminized HMX and CL-20 increases, which are in accord with the experiment of aluminized RDX.

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Publication details

The article was received on 06 Aug 2018, accepted on 23 Oct 2018 and first published on 23 Oct 2018


Article type: Paper
DOI: 10.1039/C8CP05006F
Citation: Phys. Chem. Chem. Phys., 2018, Accepted Manuscript
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    Reactive Molecular Dynamic Simulation of Thermal Decomposition for Nano-Aluminized Explosives

    Z. Mei, Q. An, F. Zhao, S. Xu and X. Ju, Phys. Chem. Chem. Phys., 2018, Accepted Manuscript , DOI: 10.1039/C8CP05006F

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