Thermal Initiation of Al-MoO3 Nanocomposite Materials Prepared by Different Methods

Stamatis, Demitrios; Dreizin, Edward L.; Higa, Kelvin T.

doi:10.2514/1.55600

Cited by 9 publications

(11 citation statements)

References 21 publications

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“…The nanocomposite powder used in this work, metal-rich thermite 8Al · MoO 3 produced by ARM, has been used in several recent studies focused on its ignition and combustion [17,[25][26][27]. It was prepared using an aluminum powder, nominal particle size under 44 mm, 99.5 % purity by Atlantic Equipment Engineers and molybdenum oxide powder, nominal particle size under 44 mm, 99.95 % purity by Alfa Aesar.…”

Section: Methodsmentioning

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: Methodsmentioning

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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“…Burning particles that were much finer than the pellet were ejected as the combustion propagated downward through the pressed samples. Samples 3,4,[12][13][14]20,22,25 showed this behavior.I na ll cases, ejection removed substantial fraction of material fromt he burning pellets. Figure 7s hows an illustration of this combustion regime for sample 14.…”

Section: (Iii)propagation With Ejection Offine Fragmentsmentioning

confidence: 84%

“…Al ist of the starting materials, their purity and the compositions of prepared nanocomposites areg iveni nT able 1. ARM was used extensively to preparev ariety of reactive materials in the past, e.g., [ 9,23,[25][26][27]; here it was used to prepare 2B-Ti, 2B-Zr, Ti-C, Mg-S, and Al-MoO 3 nanocomposite powders. As haker mill (SPEX Certiprep, 8000 series) with two 50 mL flatended steel vials cooled byr oom-temperature air jets was used to preparea ll composites except for Mg-S. Case-hardened carbon steel balls 0.95 cm diameter,w ere used as am illing media.…”

Section: Materials Preparationmentioning

confidence: 99%

“…It was,h owever, difficult to determine in which systems, reactions of Sm with other componentsa re least likely to occur. Ap reliminary survey aimed to select reactive systems for which high reaction rates and temperatures were reported experimentally,e nabled us to narrow down the compositions to be explored to 2B-Ti [ 9,14,15], 2B-Zr [16,17],T i-C [18][19][20][21], Mg-S [22],a nd at hermite system Al-MoO 3 with differentf uel/oxidizer ratios [23][24][25][26]. The above list of possible compositions is not exhaustive; however,i tc onsiders distinctly different types of reactive materials.…”

Section: Introductionmentioning

confidence: 99%

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Reactive Materials for Evaporating Samarium

Abraham

MacDonald

Dreizin

2016

Propellants Explo Pyrotec

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Different reactive materials were prepared and evaluated as potential heaters to evaporate refractory and readily ionized samarium metal. Fully dense, nanocomposite powders of thermites and boride‐forming compounds were prepared using arrested reactive milling. In some samples, samarium powder was blended with the nanocomposite powders; in other samples samarium was added using an additional short milling step. Powders were pressed in pellets and ignited at a low pressure. Flame propagation was monitored optically; combustion products were collected and analyzed. It was observed that nanocomposite 2B‐Ti powder, in which samarium was added via an additional milling step was most suitable for evaporating samarium, while preventing its reaction with other material components. Up to 30 wt‐% of samarium could be added and most of it evaporated in the presented experiments.

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“…In addition, the gas release to the atmosphere would be so slow as to be undetectable. Finally, it is interesting to comment that in the heated filament experiments, the ignition of the ARM-prepared thermites occurs at temperatures that are very close to the ignition temperatures for the nano-thermites prepared using blends of nano-sized aluminum powders [140]. Although natural oxide exists on surface of individual aluminum nanoparticles, it was suggested above that a new heterogeneous reaction surface may be produced in such materials as a result of reactive sintering.…”

Section: Model Parametermentioning

confidence: 97%