Molecular dynamics study of sintering of Al nanoparticles with/without organic coatings

Liu, Junpeng; Wang, Mengjun; Sun, Ruochen; Yang, Yanxi; Zou, G. W.

doi:10.1016/j.commatsci.2020.110265

Cited by 23 publications

(4 citation statements)

References 31 publications

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“…Alavi used MD simulations to predict the melting points of ANPs, and the simulation results were in agreement with the experimental results . Much work has been devoted to exploring the sintering of metal nanoparticles by molecular dynamics (MD) simulations. − Koraychy et al studied the coalescence and surface deposition process of two Al and Ni nanoparticles . They found that the degree of coalescence and deposition was strongly temperature dependent, and the deposition rate increases with the temperature, while the sintering and deposition of heteronanoparticles are more significant at lower temperatures than melting.…”

Section: Introductionmentioning

confidence: 76%

Combustion of Al Nanoparticles Coated with Nitrocellulose/Ethanol/Ether Molecules by Equilibrium Molecular Dynamics Simulations

Chu,

Wang,

Liu

et al. 2023

ACS Omega

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Al nanoparticles (ANPs) have high reactivity, but they are easily inactivated by external oxidants. To improve their surface properties, we coat ANPs with a nitrocellulose (NC)/ethanol/ether solution. Comparative discussions are raised from the coating to the combustion process. Our results show that NC/ethanol/ether forms a dense coating layer on the surface of annealed ANPs and passivates ANPs through physical and chemical adsorption. The coating layer can block the contact between the active Al atoms and O 2 molecules at low temperatures. In the ignition phase, the NC/ethanol/ether coating layer can increase the density of the O 2 molecules around the ANPs and the surface temperature of ANPs. At the end of the ignition phase, the number of O atoms adsorbed on the surface of NC/ethanol/ether coating-passivated ANPs (csANPs) and NC/ethanol/ether coating-annealed ANPs (cANPs) increased by about 60 and 50%, respectively, compared with passivated ANPs (sANPs). Since the desorption and diffusion of the coating layer will expose more reaction sites, ANPs have a shorter ignition delay and a lower ignition temperature. According to the change in atomic displacement, the combustion stage can be divided into three stages: surface oxidation/core melting diffusion, combustion inward propagation, and uniform combustion. The decomposition of NC molecules can increase the combustion speed, combustion time, and efficiency of ANPs. Such improvement will enable ANPs to obtain better storage and combustion performance and play a stronger role in the field of energetic materials.

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Section: Introductionmentioning

confidence: 76%

Combustion of Al Nanoparticles Coated with Nitrocellulose/Ethanol/Ether Molecules by Equilibrium Molecular Dynamics Simulations

Chu,

Wang,

Liu

et al. 2023

ACS Omega

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“…The ReaxFF MD method is currently used in a wide range of reaction systems, information on which can be found in the references Ref. [10][11][12][13].…”

Section: Reaxff Molecular Dynamicsmentioning

confidence: 99%

Molecular Dynamics Simulation of the Pyrolysis and Oxidation of NEPE Propellant

Wen

Wang³

et al. 2022

Propellants Explo Pyrotec

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NEPE propellant is a new type of propellant with high energy and good low-temperature mechanical properties. However, due to the lack of detailed research on its microscopic pyrolysis and oxidation mechanism, its combustion performance is challenging to regulate, limiting the further development. Therefore, a core-shell nanoparticle model (Al/Al 2 O 3 /HMX/NEPE) with 12257 atoms is constructed in this paper. Based on the above force field, we mainly analyze the behavior of high temperature pyrolysis. At the same time, key intermediate products and key original reactions are obtained. It is found that the pyrolysis and oxidation of NEPE propellant can be roughly divided into three stages: (1) Pyrolytic warming stage (0-200 ps),(2) Rapid reaction stage (200-400 ps), (3) Stable reaction stage (400-1200 ps). The pyrolysis and oxidation of HMX/ NEPE on the Al(Aluminium) core surface is essentially a gradual fracture of the macromolecular structure. Due to high temperature pyrolysis, a large amount of NO 2 , NO, NH and NH 2 are produced in the system. NO, NO 2 interacts with NH and NH 2 , resulting in the rapid accumulation of N 2 and H 2 O while generating a large amount of heat, which is the main reason for the heating of the system. The present study would contribute to the formulation design and combustion performance regulation of NEPE solid propellants, which is an essential reference value.

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“…However, these studies only described the fusion behavior of the two metal nanoparticles during the heating process when the sintering temperature (T s ) is above the melting point (T m ), which are totally different from solid-phase sintering (T s ≈ 2/3 T m ). In addition, some sintering densification simulation 26,27 were performed at a constant temperature, whereas the actual sintering process goes through a nonequilibrium heating process. Therefore, the sintering mechanism how the heating stage changes the densification process has not been well understood.…”

Section: Introductionmentioning

confidence: 99%

The effect of heating rate on sintering mechanism of alumina nanoparticles

et al. 2022

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The densification process of sintered alumina is mainly controlled by surface, lattice, and interface diffusion, and many experimental researches show that heating rate can affect the transfer of matter. Thus, to further reveal the effect of heating rate on sintering mechanism of alumina nanoparticle, molecular dynamic simulations were performed at five different heating rates to examine the migration of atoms and evolution of microstructure in heating stage. Results show that the sintering process of heating is a typical thermal activation process. High displacement response temperature is caused by high heating rate, which results in the mechanism of atomic migration quickly changing from surface diffusion to overlapping of surface, interface, and lattice diffusion. Nonuniform microstructure and asymmetrical sintered neck forms due to unstable and nonuniform mass transfer. Sintered neck with small radius of curvature leads to high shrinkage rate and large driving force. The sintering mechanism is expected to be helpful for understanding or developing new fast sintering methods for ceramics.

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Molecular dynamics study of sintering of Al nanoparticles with/without organic coatings

Cited by 23 publications

References 31 publications

Combustion of Al Nanoparticles Coated with Nitrocellulose/Ethanol/Ether Molecules by Equilibrium Molecular Dynamics Simulations

Combustion of Al Nanoparticles Coated with Nitrocellulose/Ethanol/Ether Molecules by Equilibrium Molecular Dynamics Simulations

Molecular Dynamics Simulation of the Pyrolysis and Oxidation of NEPE Propellant

The effect of heating rate on sintering mechanism of alumina nanoparticles

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