Oxidation of nanocrystalline aluminum by variable charge molecular dynamics

Perron, Aurélien; Garruchet, Sébastien; Politano, O.; Aral, Gurcan; Vignal, V.

doi:10.1016/j.jpcs.2009.09.008

Cited by 28 publications

(26 citation statements)

References 39 publications

(53 reference statements)

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“…Great attentions had been paid to aluminum nanoparticles because of their superior performances in burning and energy release, which is expected to solve the problems of aluminum micro-particles, existed in propellants 3–5 . The burning rate of the solid rocket propellants is one of the most important factors that determine the performance of rocket 6 .…”

Section: Introductionmentioning

confidence: 99%

Preparation of mono-dispersed, high energy release, core/shell structure Al nanopowders and their application in HTPB propellant as combustion enhancers

Wang

Shangguan³

et al. 2017

Sci Rep

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Mono-dispersed, spherical and core/shell structure aluminum nanopowders (ANPs) were produced massively by high energy ion beam evaporation (HEIBE). And the number weighted average particle size of the ANPs is 98.9 nm, with an alumina shell (3-5 nm). Benefiting from the passivation treatment, the friction, impact and electrostatic spark sensitivity of the ANPs are almost equivalent to those of aluminum micro powders. The result of TG-DSC indicates the active aluminum content of ANPs is 87.14%, the enthalpy release value is 20.37 kJ/g, the specific heat release S 1 /Δm 1 * (392-611 °C) which determined the ability of energy release is 19.95 kJ/g. And the value of S 1 /Δm 1 * is the highest compared with ANPs produced by other physical methods. Besides, the ANPs perfectly compatible with hydroxylterminated polybutadiene (HTPB), 3 wt. % of ANPs were used in HTPB propellant replaced micron aluminum powders, and improved the burning rate in the 3-12 MPa pressure range and reduced the pressure exponential by more than 31% in the 3-16 MPa pressure range. The production technology of ANPs with excellent properties will greatly promote the application of ANPs in the field of energetic materials such as propellant, explosive and pyrotechnics.The large specific surface area, high density, low consumption of oxygen, high volumetric heat of combustion and high reactivity made ANPs can be broadly used in propellants 1, 2 . Great attentions had been paid to aluminum nanoparticles because of their superior performances in burning and energy release, which is expected to solve the problems of aluminum micro-particles, existed in propellants 3-5 . The burning rate of the solid rocket propellants is one of the most important factors that determine the performance of rocket 6 . The typical diameter of aluminum particles used in propellants is in the order of ~30 μm 7 . The burning rate of propellants can be increased by employing aluminum powders with higher specific surface area 8,9 . Replacement of micro-aluminum powders by ANPs will increase the propellant burning rate by ~100% and always show low pressure-exponents in 1-12 MPa pressure range 10 . Besides, the burning rate of the solid propellants increases depending on the percentage of high-energy matters, ANPs, in the propellant content 6 .ANPs have small size and surface effects, and their surface atoms are not matched, which leads to the particles are in highly active state 2 . The high reactivity of ANPs have also caused aging problems, particularly in an environment of high relative humidity 11 . Another problem of using ANPs as additives in propellants is the original agglomeration, leading to heterogeneity of the mixtures and to coalescence of agglomerates in the heat penetration zone during combustion 12 . The near-surface combustion of ANPs controls the propellant burning rate, the high agglomeration level of ANPs points to low exponent of burning rate 10 . In order for any energetic material to have application, it must be sensitive enough to various stimuli to combus...

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Section: Introductionmentioning

confidence: 99%

Preparation of mono-dispersed, high energy release, core/shell structure Al nanopowders and their application in HTPB propellant as combustion enhancers

Wang

Shangguan³

et al. 2017

Sci Rep

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“…35, 36 Puri and Yang 37 performed MD simulation to study the thermo-mechanical behavior of nano-Al particles coated with crystalline and amorphous oxide layers. Perron et al 38 have studied the oxidation of multi-grain nanocrystalline (mean grain size ¼ 5 nm) Al surfaces in the temperature range 300-750 K using variable charge molecular dynamics simulations. Structures of cand amorphous Al 2 O 3 have been investigated using MD and density function theory (DFT) by Gutierrez et al 39,40 Vashishta et al 41 have developed an interaction potential consisting of two-and three-body terms for alumina to simulate the amorphous and liquid phases.…”

Section: Introductionmentioning

confidence: 99%

Size effect on the oxidation of aluminum nanoparticle: Multimillion-atom reactive molecular dynamics simulations

Liu

Kalia

Nakano

et al. 2013

Journal of Applied Physics

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Articles you may be interested inCooling rate and size effects on the medium-range structure of multicomponent oxide glasses simulated by molecular dynamics Size effects in the infrared spectra of N H 3 ice nanoparticles studied by a combined molecular dynamics and vibrational exciton approachThe size effect in the oxidation of aluminum nanoparticles (Al-NPs) has been observed experimentally; however, the mechano-chemistry and the atomistic mechanism of the oxidation dynamics remain elusive. We have performed multimillion atom reactive molecular dynamics simulations to investigate the oxidation dynamics of Al-NPs (diameters, D ¼ 26, 36, and 46 nm) with the same shell thickness (3 nm). Analysis of alumina shell structure reveals that the shell of Al-NPs does not break or shatter, but only deforms during the oxidation process. The deformation depends slightly on the size of Al-NP. This reaction from the oxidation heats the Al-NP to a temperature of T > 5000 K. Ejection of Al atoms from shell starts earlier in small Al-NPs-at t 0 ¼ 0.18, 0.28 and 0.42 ns for D ¼ 26, 36 and 46 nm, when they all have the same shell temperature of 2900 K. As the oxidation dynamics proceeds, the total system temperature (including the environmental oxygen) increases monotonically; however, the time derivative of the total temperature, (dT system /dt), reaches a maximum at t 1 ¼ 0.20, 0.32 and 0.51 ns for D ¼ 26, 36 and 46 nm. At this peak value of (dT system /dt), the shell temperature for the three Al-NPs are 3100 K, 3300 K, and 3500 K, respectively. The time lag between t 1 and t 0 is 0.02, 0.04 and 0.09 ns for D ¼ 26, 36 and 46 nm clearly indicates the size effect.

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“…Variable charge methods allow studying oxidation of metals, [34][35][36] metal alloys, 37 dissimilar metal/metal oxide interfaces, 37 combustion chemistry, 34 etc. For example, one of the variable-charge potential schemes was proposed by Streitz and Mintmire to treat the atomic charges as dynamic variables and was successfully applied to explore the oxidation mechanism of metallic Al nano systems as a function of temperature, oxygen pressure, and orientation of the aluminum substrate.…”

Section: Computational Approach and Methodsmentioning

confidence: 99%

“…For example, one of the variable-charge potential schemes was proposed by Streitz and Mintmire to treat the atomic charges as dynamic variables and was successfully applied to explore the oxidation mechanism of metallic Al nano systems as a function of temperature, oxygen pressure, and orientation of the aluminum substrate. [33][34][35][36]38 Our MD simulations were carried out using the variable-charge scheme, known as the ReaxFF model, which can simulate the temporal evolution of atomic charges resulting from changes in the local environment with significantly lower amount of computational cost than is required when the quantum-based computational methods are employed. 39 The most important feature of using the ReaxFF model to describe both covalent and (partially) ionic bonds, as well as the entire range of intermediate interactions, is that it can accurately describe mechanically induced chemical reactions by mechanical stretching, which is characterized by bond straightening, bond breakage, bond formation, inner atomic distortion, and rupture for pure and oxidized Fe NW systems.…”

Section: Computational Approach and Methodsmentioning

confidence: 99%

Effects of oxidation on tensile deformation of iron nanowires: Insights from reactive molecular dynamics simulations

Aral

Wang

Ogata

et al. 2016

Journal of Applied Physics

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The influence of oxidation on the mechanical properties of nanostructured metals is rarely explored and remains poorly understood. To address this knowledge gap, in this work, we systematically investigate the mechanical properties and changes in the metallic iron (Fe) nanowires (NWs) under various atmospheric conditions of ambient dry O 2 and in a vacuum. More specifically, we focus on the effect of oxide shell layer thickness over Fe NW surfaces at room temperature. We use molecular dynamics (MD) simulations with the variable charge ReaxFF force field potential model that dynamically handles charge variation among atoms as well as breaking and forming of the chemical bonds associated with the oxidation reaction. The ReaxFF potential model allows us to study large length scale mechanical atomistic deformation processes under the tensile strain deformation process, coupled with quantum mechanically accurate descriptions of chemical reactions. To study the influence of an oxide layer, three oxide shell layer thicknesses of $4.81 Å , $5.33 Å , and $6.57 Å are formed on the pure Fe NW free surfaces. It is observed that the increase in the oxide layer thickness on the Fe NW surface reduces both the yield stress and the critical strain. We further note that the tensile mechanical deformation behaviors of Fe NWs are dependent on the presence of surface oxidation, which lowers the onset of plastic deformation. Our MD simulations show that twinning is of significant importance in the mechanical behavior of the pure and oxide-coated Fe NWs; however, twin nucleation occurs at a lower strain level when Fe NWs are coated with thicker oxide layers. The increase in the oxide shell layer thickness also reduces the external stress required to initiate plastic deformation. Published by AIP Publishing.

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Oxidation of nanocrystalline aluminum by variable charge molecular dynamics

Cited by 28 publications

References 39 publications

Preparation of mono-dispersed, high energy release, core/shell structure Al nanopowders and their application in HTPB propellant as combustion enhancers

Preparation of mono-dispersed, high energy release, core/shell structure Al nanopowders and their application in HTPB propellant as combustion enhancers

Size effect on the oxidation of aluminum nanoparticle: Multimillion-atom reactive molecular dynamics simulations

Effects of oxidation on tensile deformation of iron nanowires: Insights from reactive molecular dynamics simulations

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