Ignition and combustion of boron-based Al·B·I2 and Mg·B·I2 composites

Wang, Song; Abraham, Ani; Zhong, Ziyue; Schoenitz, Mirko; Dreizin, Edward L.

doi:10.1016/j.cej.2016.02.071

Cited by 30 publications

(16 citation statements)

References 31 publications

(44 reference statements)

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“…This is caused by the co‐oxidation of both B NPs and Al NPs (see in Figure S2). Al NPs can react with oxygen to form Al 2 O 3 and can also react with B 2 O 3 to remove the oxide layer on the surface of B NPs . Thereby, B NPs can be rapidly oxidized, resulting in a sharp increase in the amount of released heat.…”

Section: Resultsmentioning

confidence: 99%

Preparation and Combustion Performance of B/PVDF/Al Composite Microspheres

Cheng

Huang

Yang

et al. 2019

Propellants Explo Pyrotec

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In order to solve the problems that boron nanoparticles (B NPs) are easy to agglomerate, low in combustion efficiency and difficult to ignite, 80 nm B NPs were doped with 50 nm aluminum nanoparticles (Al NPs) by electrospraying using 10 wt % PVDF as binders. The prepared B/PVDF/Al composite microspheres with diameter of 1∼5 μm were examined by scanning electron microscopy (SEM). Elemental maps confirmed the uniform distribution of B and Al NPs with the coating of polyvinylidene fluoride (PVDF). The thermal properties were tested by thermogravimetry‐differential scanning calorimetry (TG‐DSC), and the combustion process of samples in air was recorded by a high‐speed camera. The results showed that PVDF can reacted with the oxide layer on the surface of Al (Al2O3) and B (B2O3) NPs to promote the combustion and energy release of B/PVDF/Al. In addition, the thermal reactivity of B/PVDF/Al increased as the Al NPs content increases. Al NPs could reduce the ignition energy of B/PVDF/Al, allowing it to burn stably in air. A thermal reaction mechanism was proposed to explain qualitatively the four‐stage pattern of B/PVDF/Al decomposition observed in TG‐DSC curves.

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Section: Resultsmentioning

confidence: 99%

Preparation and Combustion Performance of B/PVDF/Al Composite Microspheres

Cheng

Huang

Yang

et al. 2019

Propellants Explo Pyrotec

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“…A [ms mm Àn ] n Al [10] 4.55 0.50 B [28] 4.73 0.75 Al · Ca(IO 3 ) 2 6.61 0.52 B · Ca(IO 3 ) 2 10.81 0.27…”

Section: Methodsunclassified

“…Assuming that larger particles burn longer, the distributions of pulse durations were correlated with the respective distributions of particle sizes ( Figure 2). This experimental technique and data processing methodology was extensively discussed in the literature [10,[24][25][26][27][28]32].…”

Section: Ignition and Combustion Experimentsmentioning

confidence: 99%

“…Based on correlation between statistical distribution of pulse durations and particle size distributions shown in Figure 2, particle combustion times as a function of their sizes were obtained and plotted in Figure 6. For comparison, data for pure aluminum [10] and boron particles [28] are also shown. Both reference data sets for pure elements were obtained using the same experimental methodology as in this work.…”

Section: Particle Combustionmentioning

confidence: 99%

“…Elemental iodine has been incorporated into various metal-based fuel systems [10][11][12][13][14][15]. However, the prepared composites could contain only up to 20 wt % of iodine to remain sufficiently stable to be handled.…”

Section: Introductionmentioning

confidence: 99%

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Nanocomposite Thermites with Calcium Iodate Oxidizer

Wang

Liu

Schoenitz

et al. 2017

Prop., Explos., Pyrotech.

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Iodine bearing reactive materials and fuel additives are being developed to inactivate harmful aerosolized spores and bacteria by combined thermal and chemical effects. Nanocomposite thermites with aluminum and boron serving as fuels and calcium iodate as an oxidizer were prepared by arrested reactive milling. Both materials contained 80 wt % of calcium iodate. Morphology and particle sizes of the prepared materials were characterized using scanning electron microscopy (SEM). Both powders comprised particles finer than ca. 10 μm with fuel and oxidizer mixed on the submicrometer scale. Powders were exposed to room air to assess their stability. They were ignited as a thin coating on an electrically heated filament. Powders were injected in an air‐acetylene flame to observe combustion of individual particles. Pressed pellets for both prepared materials were prepared and ignited using a CO2 beam. Al ⋅ Ca(IO3)2 oxidizes rapidly in room air, whereas no aging was detected for B ⋅ Ca(IO3)2. Ignition of Al ⋅ Ca(IO3)2 occurs around 1150 K, after both aluminum and calcium iodate melt. Ignition is accompanied by ejection of sintered particles undergoing microexplosions while they are combusting. Ignition of B ⋅ Ca(IO3)2 occurs between 600 and 700 K, before either of the components melt. Combustion is accompanied by the formation of a luminous halo above the material, suggesting a vapor‐phase reaction involving boron suboxides. Longer ignition delays are observed for the pellets of Al ⋅ Ca(IO3)2 heated by the CO2 laser beam compared to similar pellets of B ⋅ Ca(IO3)2. Burn rates of B ⋅ Ca(IO3)2 pellets are nearly twice as fast as those of Al ⋅ Ca(IO3)2, primarily due to the lower ignition temperature for the boron‐based thermite. The flame temperatures obtained from the time‐integrated optical spectra are close to 2140 and 2060 K for Al ⋅ Ca(IO3)2 and B ⋅ Ca(IO3)2, respectively. Individual particles of B ⋅ Ca(IO3)2 injected into an air‐acetylene flame burn slower than similar Al ⋅ Ca(IO3)2 particles. Based on their better stability, lower ignition temperatures, shorter ignition delays, and longer burn times leading to a more gradual release of iodine, B ⋅ Ca(IO3)2 composites are suggested to be better suited as components of energetic formulations aimed to defeat stockpiles of biological weapons.

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Reactive Structural Materials: Preparation and Characterization

Hastings

Dreizin

2017

Adv Eng Mater

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Reactive structural materials, which can serve both as structural elements as well as a source of chemical energy released upon initiation have emerged as an important class of metal-based composites for use in various energetic systems. Such materials rely on a variety of exothermic reactions, from oxidation to formation of metal-metalloid and intermetallic phases. The rates of these reactions are as important as the energy that may be released, in order for them to occur at the time scales compatible with the requirements of applications. Therefore, chemical composition, scale at which reactive components are mixed, and the structure and morphology of materials are important and can be controlled by the method of preparation and compaction of the composite materials. Methods of preparation of the composite structures are briefly reviewed as well as methods of characterization of their mechanical and energetic properties. In addition to common thermo-analytical and static mechanical property measurements, dynamic tests of mechanical properties as well as ignition and combustion experiments are necessary to understand the fragmentation, initiation, and heat release expected for these materials when they are stimulated by an impact, shock, or rapid heating. Reaction mechanisms are studied presently for the thin layers and small samples of reactive materials initiated in carefully designed experiments. In other experiments, impact and explosive initiation are characterized for larger material compacts in the conditions imitating practical scenarios. Examples of results describing thermal, impact, and explosive initiation of some of the reactive materials are presented.

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Ignition and combustion of boron-based Al·B·I2 and Mg·B·I2 composites

Cited by 30 publications

References 31 publications

Preparation and Combustion Performance of B/PVDF/Al Composite Microspheres

Preparation and Combustion Performance of B/PVDF/Al Composite Microspheres

Nanocomposite Thermites with Calcium Iodate Oxidizer

Reactive Structural Materials: Preparation and Characterization

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