Effect of polymorphic phase transformations in Al2O3 film on oxidation kinetics of aluminum powders

Trunov, Mikhaylo; Schoenitz, Mirko; Zhu, Xiaoying; Dreizin, Edward L.

doi:10.1016/j.combustflame.2004.10.010

Cited by 472 publications

(283 citation statements)

References 25 publications

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“…Some structural changes did not appear while strong particles aggregates did appear. A brief approach to oxidative conditions was carried out, through TG measurements in air, in temperatures up to 900°C, confirming Trunov's [2] results. Moreover, under oxidative conditions, coalescence of particles was reduced when compared to inert conditions [4].…”

Section: Introductionsupporting

confidence: 75%

“…Trunov et al [2] studied the influence of the heating rate on different powders under pure oxygen flow for combustion processes using thermogravimetry (TG) and X-ray diffraction (XRD). Higher heating rates shifted all the oxidation processes toward higher temperatures, with ignition temperatures depending on particle size.…”

Section: Introductionmentioning

confidence: 99%

“…The majority of efforts has been devoted to the use of aluminium powder as an additive for propellants, explosives and pyrotechnics. For example, particle size influence on ignition temperatures for explosives has been summarised elsewhere [2], for temperatures ranging from 650 to 2,000°C.…”

Section: Introductionmentioning

confidence: 99%

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Oxidation of Micro-Sized Aluminium Particles: Hollow Alumina Spheres

et al. 2013

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Oxidized aluminium microparticles have recently been proposed for manufacturing new, environmentally-friendly, protective coatings on stainlesssteels and Ni-base alloys. The oxidation mechanisms of spherical aluminium microparticles of an average particle size of 3.5 lm were studied. Accordingly, simultaneous differential thermal analysis-thermogravimetry tests were carried out in air at different temperatures, always above aluminium melting temperature. Scanning electron microscopy and XRD were also used for the interpretation of results. Weight gain and energy results were explained in terms of the different structural changes taking place in aluminium particles. Dehydroxylation process was identified. The transformation of amorphous alumina to c-Al 2 O 3 was numerically evaluated and the alumina phase transformation (c-Al 2 O 3 ?a-Al 2 O 3 ) was also studied. The temperature ranges revealed the appearance of metastable phases (h-Al 2 O 3 ). Complete oxidation of particles can be obtained at 1,300°C in \1 h, although this also takes place at lower temperatures if enough oxidation time is used. Activation energy of oxidation process at high temperature was also estimated, taking a value of 334 kJ/mol. High temperature oxidation causes the formation of hollow alumina spheres, without any aluminium left inside them.

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Section: Introductionsupporting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

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Oxidation of Micro-Sized Aluminium Particles: Hollow Alumina Spheres

et al. 2013

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“…Phase transitions of the Al 2 O 3 shell were identified in this study. The Al 2 O 3 crystal transitions followed the sequence identified by Trunov et al [47] [48], simplified Al 2 O 3 polymorphic phase transition during particle oxidation is known (1).…”

Section: Experimental Data On the Nal Slow Oxidationmentioning

confidence: 99%

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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“…While some studies suggested that it was a fixed value around the melting temperature of the aluminum particles [21,24], many others suggest that the ignition temperature is not a material property but depends upon the environmental variables, such as the heating rates [25][26][27], particle size [28], specific experimental conditions or methods employed [29,30] and instruments used [29,31,32]. It is still debatable if the ignition of aluminum nanoparticles occurred before or after the melting temperature of aluminum.…”

Section: Influence Of the Heating Ratementioning

confidence: 99%

Exothermic characteristics of aluminum based nanomaterials

et al. 2015

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Nano-structured energetic materials have been recently proposed as novel energy storage media where the exothermic reaction is the key to control the heat release process. The properties of nanoalloys, which can be engineered not only by the particle size, but also by varying their elemental compositions, are very appealing. This work conducts a comparative experimental study of the exothermic characteristics of two nanomaterials in the air, aluminum nanoparticles (nAl) and aluminum-copper nanoalloys (nano-AlCu) based on TGA/DSC studies. The results show that the general exothermic characteristics of nano-AlCu are very similar to that of nAl but the nano alloy is more reactive. The nano-AlCu oxides and ignites at lower temperature, and influenced by the heating rate. An early ignition is found for both nanomaterials, and melting of the nano-alloy is believed to be responsible for its early ignition.

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Effect of polymorphic phase transformations in Al2O3 film on oxidation kinetics of aluminum powders

Cited by 472 publications

References 25 publications

Oxidation of Micro-Sized Aluminium Particles: Hollow Alumina Spheres

Oxidation of Micro-Sized Aluminium Particles: Hollow Alumina Spheres

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

Exothermic characteristics of aluminum based nanomaterials

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