Passivation process for superfine aluminum powders obtained by electrical explosion of wires

Kwon, Young-Soon; Gromov, A. A.; Ilyin, Alexander P.; Rim, Geun-Hie

doi:10.1016/s0169-4332(03)00059-x

Cited by 96 publications

(52 citation statements)

References 15 publications

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“…The formation of nano γ-Al 2 O 3 by slow non-isothermal oxidation (0.5-20.0 K/min) occurs at low temperatures (T = 673-773 K) for electroexplosive nAl [23]. Furthermore, the different definitions of the intense oxidation onset temperature and other parameters on the DTA/DSC/TGA curves can lead to confusing comparisons Copyright © 2017 Institute of Industrial Organic Chemistry, Poland between different datasets [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]. For certain nAl samples with a specific surface area 12 m 2 /g, the mass fraction of micron-sized particle clusters (1-3 µm) could be 68 wt.%, but the number of clusters was only 2% of the total number of particles [56].…”

Section: Analysis Of Powder Characteristics and Their Comparison Withmentioning

confidence: 99%

“…Immediately after production, the nAl powders require passivation or coating procedures to avoid self-ignition and self-sintering of the particles [23][24][25][26][27]. nAl, obtained in inert gas media (argon, nitrogen or their mixtures) by any of the existing methods, is normally pyrophoric in air, because the amount and the rate of heat release from the oxidation reaction is high enough to heat the nanoparticle to its ignition temperature (~670 K for 100 nm nAl particles).…”

Section: Introductionmentioning

confidence: 99%

“…The TEM images reported in [23][24][25] show the typical structure of airpassivated nAl, with an Al core surrounded by an Al 2 O 3 shell. Fresh air-passivated nAl particles are usually characterized by Al 2 O 3 shell thicknesses in the range 2 nm to 6 nm, irrespective of particle size.…”

Section: Introductionmentioning

confidence: 99%

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Nanoaluminium: is there any Relationship between Powder Particles’ Size, Non-Isothermal Oxidation Data and Ballistics?

Gromov¹,

Teipel²

2017

Cent. Eur. J. Energ. Mater.

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This article focuses on data analyses and comparisons for aluminium nanopowders (or nanoaluminium, nAl) reactions under slow (0.5-20.0 K/min, using DTA/DSC/TGA) and fast (>10000 K/min, combustion in solid propellant formulations) non-isothermal oxidation. Particle sizes were defined through the BET method. Active Al content was related with the averaged reactivity parameters, taken from published DTA/DSC/TGA data. The specific oxidation onset temperature for nAl was poorly correlated with the BET particle size under the conditions investigated. Furthermore, the BET particle size exhibited no correlation with the observed ballistic response (burning rate) at 3.0 MPa. A logarithmic correlation y = 17.484 ln(x) -5813, with R² = 0.73, was found between nAl particle size and its aluminium content. A calibration equation for the oxidation onset temperature as a function of nAl particle size was determined as y = −0.0071x 2 + 3.3173x + 479.32, with R² = 0.75. Specific features of the nAl (metallic aluminum content in nAl and the oxidation onset temperature) can be predicted based on the measured powder parameters (such as BET particle size).

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Section: Analysis Of Powder Characteristics and Their Comparison Withmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nanoaluminium: is there any Relationship between Powder Particles’ Size, Non-Isothermal Oxidation Data and Ballistics?

Gromov¹,

Teipel²

2017

Cent. Eur. J. Energ. Mater.

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“…It has been shown that treating Al nanoparticles with long chain carboxylic acids [47,48] or perfluoroalkyl carboxylic acids [49] increases the active aluminum content compared to unpassivated Al nanoparticles, owing to the surface oxidation of the unpassivated particles. The major drawback with utilizing organic capping groups is the lowering of weight percent active Al compared to the content of organic material.…”

Section: Ii12 Synthesis and Functionalization Of Aluminum Nanopartimentioning

confidence: 99%

Nano Engineered Energetic Materials (NEEM)

Dlott¹,

Eden²,

Girolami³

et al. 2011

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The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. The ARO Nano Engineered Energetic Materials (NEEM) MURI program has been exploring new methodologies for developing energetic material formulations with control of all constituents over a wide range of length scales from 1 nm to 1 mm and larger and employing the latest techniques in molecular self-assembly and supramolecular chemistry for synthesizing and assembling NEEMs. The synthetic efforts have been guided by theoretical calculations and dynamic performance testing methodologies that also operate on all length scales. This final report ABSTRACTThe ARO Nano Engineered Energetic Materials (NEEM) MURI program has been exploring new methodologies for developing energetic material formulations with control of all constituents over a wide range of length scales from 1 nm to 1 mm and larger and employing the latest techniques in molecular self-assembly and supramolecular chemistry for synthesizing and assembling NEEMs. The synthetic efforts have been guided by theoretical calculations and dynamic performance testing methodologies that also operate on all length scales. This final report provides a summary of the accomplishments. In particular, new methods to generate metal nanoclusters were developed that are stabilized against environmental degradation while preserving their high energy content. Rapid expansion supercritical solution processes were developed and applied to synthesize nanosized particulate oxidizers and energetic oxidizer shell/fuel core composites. Surface science and experimental chemistry methods were applied to study the structures and energy releasing reaction pathways of NEEMs. Unique diagnostic capabilities were developed and applied to study the fundamental mechanisms that underlie NEEM dynamic performance. Combustion mechanisms of various NEEMs, including nanothermites and nanoparticulate fuel/liquid oxidizer systems, were experimentally analyzed. The reactive and thermal characteristics of NEEMs were studied using large (billion atoms) multiscale simulations that couple quantum-mechanical calculations to molecular dynamics calculations. In particular, the stability, structure and energetics of metallic nanoparticles with a special focus on the relationships between particle size, shape and excess surface free energy were studied. A unified theory of ignition and combustion of aluminum particles for a wide range of sizes, from nano to meso scales was established. . 12, 777-787 (2010 (b) Papers published in non-peer-reviewed journals or in conference proceedings (N/A for none)18.00 Number of Papers published in peer-reviewed journals:Number of Papers published in non peer-reviewed journals:1. USC group, "Multibillion-atom simulations of nano-mechano-chemistry on petaflops computers," First

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“…[8][9][10][11][12][13] Understanding how changes in the phase of Al2O3 can impact reactivity has important consequences for scientific and technological applications for aluminum in ceramics, catalysis, coatings, separations, [14][15][16][17][18][19][20] and energetic materials. [21][22][23][24][25] To optimize the synthesis of well-defined nanoparticles and control their reactivities, characterization tools are needed that can probe the structure of heterogenous materials over multiple length scales and under real-world conditions.…”

Section: Introductionmentioning

confidence: 99%

Chemical and Morphological Inhomogeneity of Aluminum Metal and Oxides from Soft X-ray Spectromicroscopy

Altman

Pemmaraju²,

Alayoǧlu³

et al. 2017

Inorg. Chem.

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ABSTRACT. Oxygen and aluminum K-edge X-ray absorption spectroscopy (XAS), imaging from a scanning transmission X-ray microscope (STXM), and first principles calculations were used to probe the composition and morphology of bulk aluminum metal, α-and γ-Al2O3, and several types of aluminum nanoparticles. The imaging results agreed with earlier transmission electron microscopy studies that showed a 2 to 5 nm thick layer of Al2O3 on all the Al surfaces. Spectral interpretations were guided by examination of the calculated transition energies, which agreed well with the spectroscopic measurements. Features observed in the experimental O and Al K-edge XAS were used to determine the chemical structure and phase of the Al2O3 on the aluminum surfaces. For unprotected 18 and 100 nm Al nanoparticles, this analysis revealed an oxide layer that was similar to γ-Al2O3 and comprised of both tetrahedral and octahedral Al coordination sites. For oleic-acid protected Al nanoparticles, only tetrahedral Al oxide coordination sites were observed.The results were correlated to trends in the reactivity of the different materials, which suggests that the structures of different Al2O3 layers have an important role in the accessibility of the underlying Al metal towards further oxidation.Combined, the Al K-edge XAS and STXM results provided detailed chemical information that was not obtained from powder X-ray diffraction or imaging from a transmission electron microscope.

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Passivation process for superfine aluminum powders obtained by electrical explosion of wires

Cited by 96 publications

References 15 publications

Nanoaluminium: is there any Relationship between Powder Particles’ Size, Non-Isothermal Oxidation Data and Ballistics?

Nanoaluminium: is there any Relationship between Powder Particles’ Size, Non-Isothermal Oxidation Data and Ballistics?

Nano Engineered Energetic Materials (NEEM)

Chemical and Morphological Inhomogeneity of Aluminum Metal and Oxides from Soft X-ray Spectromicroscopy

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