Melt dispersion mechanism for fast reaction of nanothermites

Levitas, Valery I.; Asay, B. W.; Son, Steven F.; Pantoya, Michelle L.

doi:10.1063/1.2335362

Cited by 186 publications

(184 citation statements)

References 12 publications

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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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Section: Influence Of the Heating Ratementioning

confidence: 99%

Exothermic characteristics of aluminum based nanomaterials

et al. 2015

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“…For pure nAl, it has been suggested that the early ignition was associated with the melting and solid phase transition of alumina [30,35]. Under very high heating rates (i.e, >10 3 K/s), the melting of aluminium would fragmentize the shell and led to a global combustion event [36]. From the DSC/TGA data and the identified first-stage reaction, Eq.…”

Section: Thermal Analysis and Reaction Kineticsmentioning

confidence: 99%

Thermal-Chemical Characteristics of Al–Cu Alloy Nanoparticles

et al. 2015

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This work investigated the oxidation, ignition and thermal reactivity of alloy nanoparticles of aluminum and copper (nAlCu) using simultaneous thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC) method. The microstructure of the particles was characterized with scanning electron microscope (SEM) and transmission electron microscope (TEM), and the elemental composition of the particles before and after the oxidation was investigated with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD).The particles were heated from room temperature to 1200 o C under different heating rates from 2 to 30 K/min in the presence of air. The complete oxidation process of the nAlCu was characterized by two exothermic and two endothermic reactions, and the reaction paths up to 1200 o C were proposed. An early ignition of nAlCu, in the temperature around 565 o C, was found at heating rates ≥ 8 K/min. The eutectic melting temperature of nAlCu was identified at ~ 546 o C, which played a critical role in the early ignition. The comparison of the reactivity with that of pure Al nanoparticles showed that the nAlCu was more reactive through alloying.

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“…This passivation shell can become an appreciable portion of the total material when the particle size approaches nanometer dimensions [16]. Levitas et al [21] proposed the following mechanism to explain the fast oxidation of Al nanoparticles. The thin oxide skins on the outside of the particles represent rigid pressure vessel walls.…”

Section: Introductionmentioning

confidence: 99%

The effect of Si–Bi2O3 on the ignition of the Al–CuO thermite

et al. 2011

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The ignition temperature of the Al-CuO thermite was measured using DTA at a scan rate of 50 C.min -1 in a nitrogen atmosphere. Thermite reactions are difficult to start as they require very high temperatures for ignition, e.g. for Al-CuO thermite comprising micron particles it is ca. 940 C. It was found that the ignition temperature is significantly reduced when the binary Si-Bi 2 O 3 system is added as sensitizer. Further improvement is achieved when the reagents are nano-sized powders. For the composition Al + CuO + Si + Bi 2 O 3 (65.3:14.7:16:4 wt %), with all components nano-sized, the observed ignition temperature is ca. 613 C and a thermal runaway reaction is observed in the DTA.

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Melt dispersion mechanism for fast reaction of nanothermites

Cited by 186 publications

References 12 publications

Exothermic characteristics of aluminum based nanomaterials

Exothermic characteristics of aluminum based nanomaterials

Thermal-Chemical Characteristics of Al–Cu Alloy Nanoparticles

The effect of Si–Bi2O3 on the ignition of the Al–CuO thermite

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