Thermal initiation of consolidated nanocomposite thermites

Stamatis, Demitrios; Dreizin, Edward L.

doi:10.1016/j.combustflame.2010.12.024

Cited by 24 publications

(8 citation statements)

References 11 publications

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“…A large surface area of the reactive interface associated with the nano-scale mixing between the fuel and oxidizer makes such materials sensitive to different ignition stimuli. Most of the quantitative measurements reported to date and characterizing reactions leading to ignition of reactive nanomaterials have relied on thermal analysis [2][3][4][5][6][7][8][9][10]. Measurements associated with faster processes have also been reported, including time-resolved mass spectrometry following ignition of nano-thermites [11][12][13], micro- [14] and nano-calorimetry [15,16], and measurements of optical emission and pressure generated by the material coated on an electrically heated filament [17,18].…”

Section: Introductionmentioning

confidence: 99%

Ignition of Nanocomposite Thermites by Electric Spark and Shock Wave

Shaw

Dlott

Williams

et al. 2014

Propellants Explo Pyrotec

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Nanocomposite 8Al ⋅ MoO3 thermite particles were prepared using arrested reactive milling and ignited using two experimental techniques. In spark ignition, a monolayer of powder was placed on a conductive substrate and heated in air by a pulsed electrostatic discharge. In shock ignition, an individual particle was targeted by a miniature, laser‐driven flyer plate accelerated to a speed in the range of 0.5–2 km s−1. In both experiments, time‐dependent optical emission produced by the ignited material was monitored and recorded. The heating rates achieved in the present experiments are on the order of 109−–1011 K s−1. These ignition methods result in a very fast combustion with characteristic burn times reduced by 1–3 orders of magnitude compared to the burn times measured previously for the same material ignited in the CO2 laser beam, where it was heated at a much lower rate of about 106−–107 K s−1. Ignition delays observed in both shock and spark ignition experiments are close to each other and vary in the range of 120–200 ns. The times of characteristic rapid increase in the optical emission of the ignited particles are also close to each other for the two experiments; however, these times are somewhat shorter (less than one μs) for the spark ignition tests compared to few μs observed for the shock initiated particles. Preliminary ideas enabling one to interpret the present results are discussed. This work establishes an approach for systematic studies of high rate ignition and respective combustion of nanocomposite reactive materials.

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Section: Introductionmentioning

confidence: 99%

Ignition of Nanocomposite Thermites by Electric Spark and Shock Wave

Shaw

Dlott

Williams

et al. 2014

Propellants Explo Pyrotec

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“…One such technique is arrested reactive milling, [17][18][19][20][21][22] which starts with large particles and mills them down until uniform nanoscale mixing is achieved. A second technique involves sputter deposition, [23][24][25][26][27] and has been used to create nanoscale multilayered geometries with controlled precision.…”

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confidence: 99%

Electrophoretic deposition and mechanistic studies of nano-Al/CuO thermites

Sullivan

Kuntz

Gash

2012

Journal of Applied Physics

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“…In order to heat the pellet surface uniformly, the laser beam was defocused so that its diameter was equal to the pellet diameter. This experimental method was described in detail elsewhere [33]. A high-speed camera (MotionPro500 by Redlake) was positioned to observe the ignition and combustion of the material.…”

Section: Ignition and Combustion Experimentsmentioning

confidence: 99%

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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Thermal initiation of consolidated nanocomposite thermites

Cited by 24 publications

References 11 publications

Ignition of Nanocomposite Thermites by Electric Spark and Shock Wave

Ignition of Nanocomposite Thermites by Electric Spark and Shock Wave

Electrophoretic deposition and mechanistic studies of nano-Al/CuO thermites

Nanocomposite Thermites with Calcium Iodate Oxidizer

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