Validation of the Thermal Oxidation Model for Al/CuO Nanocomposite Powder

Williams, Rayon A.; Schoenitz, Mirko; Dreizin, Edward L.

doi:10.1080/00102202.2013.846330

Cited by 18 publications

(14 citation statements)

References 32 publications

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“…Finally, it is discussed whether the present observations correlate with recently quantified kinetics of thermally activated reactions in nanocomposite thermites (Stamatis et al 2012;Williams et al 2014a) (Williams et al 2014c). Based on thermo-analytical measurements, the models for Al·CuO (Stamatis et al 2012;Williams et al 2013) and for Al·MoO 3 (Williams et al 2014c) nanocomposite thermites presented the redox reaction as a sequence of individual steps.…”

Section: Discussionsupporting

confidence: 56%

Electro-Static Discharge Ignition of Monolayers of Nanocomposite Thermite Powders Prepared by Arrested Reactive Milling

Monk

Williams

Liu

et al. 2015

Combustion Science and Technology

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Reactive nanocomposite powders with aluminum as a fuel and copper, bismuth, iron, and molybdenum oxide as oxidizers: 2Al·3CuO, 2.35Al·Bi 2 O 3 , 2Al·Fe 2 O 3 , and 2Al·MoO 3 , were prepared by arrested reactive milling, placed in monolayers on a conductive substrate and ignited by an electro-static discharge (ESD) or spark in air, argon, and vacuum. The ESD was produced by discharging a 2000 pF capacitor charged to a voltage varied from 5 to 20 kV. Emission from ignited particles was monitored using a photomultiplier equipped with an interference filter.Experimental variables included particle sizes, milling time used to prepare composite particles, surrounding environment, and starting ESD voltage. All materials ignited in all environments, producing individual burning particles that were ejected from the substrate. The spark duration varied from 1 to 5 µs; the duration of the produced emission pulse was in the range of 80 -250 µs for all materials studied. The longest emission duration was observed for the nanocomposite thermite using MoO 3 as an oxidizer. The reaction rates of the ESD-initiated powders were defined primarily by the scale of mixing of and reactive interface area between the fuel and oxidizer in composite materials rather than by the external particle surface or particle dimensions. In vacuum, particles were heated by ESD while remaining on the substrate until they Downloaded by [University of Nebraska, Lincoln] at 12:34 13 April 2015A c c e p t e d M a n u s c r i p t 2 began generating gas combustion products. In air and argon, particles initially pre-heated by ESD were lifted and accelerated to ca. 100 m/s by the generated shock wave; the airborne particles continued self-heating due to heterogeneous redox reactions.

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Section: Discussionsupporting

confidence: 56%

Electro-Static Discharge Ignition of Monolayers of Nanocomposite Thermite Powders Prepared by Arrested Reactive Milling

Monk

Williams

Liu

et al. 2015

Combustion Science and Technology

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“…Al$CuO [145,147] Al$MoO 3 [153] h 0 , nm 0 desired. In addition, the gas release to the atmosphere would be so slow as to be undetectable.…”

Section: Model Parametermentioning

confidence: 98%

“…A broad range of heating rates, including very low rates (0.0083e0.0033 K/min [153]) was covered experimentally and interpreted theoretically. In addition, measurements with powders prepared using different milling conditions were also well described [147]. Combining CM model with the multi-step mechanism describing polymorphic phase changes and growth of different Al 2 O 3 polymorphs enables one to quantitatively reproduce TA measurements for the ARM-prepared powders for a broad range of temperatures [145].…”

Section: Thermites Prepared As Fully Dense Nano-composite Powdersmentioning

confidence: 99%

“…Although the mechanism of the generation of the Mott potential across an interface produced between two solid reactants remains subject of active research [156], CM model was applied to such an interface earlier [157]. Following that work, and modifying the CM equations for an interface produced around a spherical oxide inclusion in a metal matrix [158], the CM model was applied to describe an early reaction in nanocomposite thermites produced by ARM [144,145,147,153,154]. Effectively, the CM reaction describes growth of the Al 2 O 3 film thickness h, as:…”

Section: Thermites Prepared As Fully Dense Nano-composite Powdersmentioning

confidence: 99%

“…Instead, it is an effective thickness of a precursor phase, which transforms into Al 2 O 3 during the reaction. Detailed analyses of TA measurements focusing on the low-temperature reactions identified the CM model parameters, which are shown in Table 6 and describe such reactions for both Al$CuO [144,145,147] and Al$MoO 3 [153] nanocomposite thermites. Term E 2 , the contribution of the Mott potential, is treated as a linear function of temperature following Ref.…”

Section: Thermites Prepared As Fully Dense Nano-composite Powdersmentioning

confidence: 99%

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