Influence of Al and Al₂O₃ Nanoparticles on the Thermal Decay of 1,3,5-Trinitro-1,3,5-triazinane (RDX): Reactive Molecular Dynamics Simulations

Abstract

Metallic additives, Al nanoparticles in particular, have extensively been used in energetic materials (EMs), of which thermal decomposition is one of the most basic properties. Nevertheless, the underlying mechanism for the highly active Al nanoparticles and their oxidized counterparts, the Al2O3 nanoparticles, influencing the thermal decay of aluminized EMs has not fully been understood. Herein, we explore the influence of Al and Al2O3 nanoparticles on the thermal decomposition of 1,3,5trinitro-1,3,5-triazinane (RDX), one of the most common EMs, based on large-scale reactive force field molecular dynamics simulations within three heating schemes (constant-temperature, programmed and adiabatic heating). The presence of Al nanoparticles significantly reduces the induction time and energy required to activate the RDX decay, and greatly increases energy release. The fundamental reason for these results is that Al changes the primary decay pathway from the unimolecular N-NO2 scission of RDX to bimolecular barrier-free or low-barrier Al-involved reactions, and possesses a strong O-extraction capability and a moderate one to react with C/H/N. It is also responsible for the growth of the Al-contained clusters. And Al2O3 nanoparticles can also demonstrate such catalysis capability but contribute less to the enhancement of energy release. Moreover, the detailed evolutions of key thermodynamic properties, intermediate and final gaseous products, and Al-contained products are also presented. Besides, under the programmed heating and adiabatic heating conditions the catalysis of the Al and Al2O3 nanoparticles becomes more distinct. Thereby, many properties of aluminized EMs are expected to well be understood by our simulation results.

Crack Mechanism of Al@Al2O3 Nanoparticles in Hot Energetic Materials

“…The reactions occur readily because they are energy barrierfree. 33,36,37,40,41 A more remarkable reduction in the potential energy of L-ANP is observed and has a relation on a higher content of the Al@Al 2 O 3 nanoparticle, compared with H-ANP. It agrees with a previous experimental research, as a high content of Al largely facilitates to increase the heat release.…”

“…In Figure 4,ba, some molecular fragments of RDX are adsorbed on the nanoparticle surface at 20 ps, due to the aforementioned no energy barrier. 36,37,40 Thereby, the oxide shell of the ANP is thickened. A significant disintegration and an evident void with very sparse particles are found in H-ANP at 21 ps, suggesting a fast shell crack and microexplosion of the entire ANP.…”

“…The reactive force field (ReaxFF) that is parameterized based on the optimized interactions between C/H/O/N and Al was employed in our MD simulations. This force field has been successfully applied to study the reactions of heated EMs, such as 1,3,5-triamino-2,4,6-trinitrobenenze (TATB) and RDX, with Al and Al 2 O 3 nanoparticles. , All the simulations and the visualization of dynamic processes were complemented by LAMMPS package and OVITO software, respectively. Our simulations proceeded by two stages: the first stage of soft oxidation at room temperature and the second one of violent combustion at a high temperature.…”

The Effects of Nano-Additives Added to Diesel-Biodiesel Fuel Blends on Combustion and Emission Characteristics of Diesel Engine: A Review

“…It has the advantage of reacting with CO, HC molecules and Carbon atoms in soot and generating large amounts of oxygen, allowing the fuel to burn thoroughly [51,52]. Hao et al [53] found that aluminium (Al) nano-additives had a strong oxygen extraction ability and could significantly reduce the induction time and energy required for catalytic exothermic reactions. Singh et al [54] found that carbon-based single-walled nanotubes and multi-walled nanotubes could dramatically increase the ignition rate, ignition delay period, and extend the total combustion time.…”

Atomic-level investigation on the oxidation efficiency and corrosion resistance of lithium enhanced by the addition of two dimensional materials

“…1,7,8 Generally, metals have traditionally been known to be good energy storage resources in addition to being effective additives in slurry fuels, energetic materials, and propellants by virtue of their high specic energy. 3,[9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] The majority of prior research on harnessing the chemical energy contained in metal fuels has concentrated on the reaction of various metals, particularly aluminum (Al) and magnesium (Mg), with water to produce hydrogen on demand, with only a few studies focusing on the combustion of metal fuels to generate heat. [12][13][14] Lately, the combustion of Li with various gaseous products has piqued interest for a multitude of reasons.…”