Gravity effects on reactive settling in the Al–W system in SHS

Unuvar, C.; Fredrick, D.; Anselmi‐Tamburini, Umberto; Shaw, Benjamin D.; Manerbino, A.; Guigné, J. Y.; Munir, Zuhair A.

doi:10.1016/j.intermet.2006.07.001

Cited by 13 publications

(11 citation statements)

References 23 publications

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“…This made it possible to apply a current of 0, 200, and 350 A, respectively, and obtain the same combustion temperature, 1600 C. The temperature was measured by a two-color infrared pyrometer (Mikron-M770S 700e1800 C) focused on the middle of one surface of the chemical oven. More details on the procedure and technique are provided in the earlier paper [23].…”

Section: Methodsmentioning

confidence: 99%

“…It consists of 20 reaction chambers, three storage drawers, a processing chamber, an electronics box, a video equipment plate, a data acquisition plate, and two power supplies. The reaction chambers were modified in order to incorporate hardware for introducing high electric current [23]. The chambers, each including a chemical oven/sample, were prepared before each flight.…”

Section: Methodsmentioning

confidence: 99%

“…The chambers, each including a chemical oven/sample, were prepared before each flight. Chemical ovens were placed in the sample holder/electrode assembly, which was described in detail elsewhere [23]. Chambers were flushed with ultra high purity argon (UHP-99.999%) and finally filled with argon at about 1 atm.…”

Section: Methodsmentioning

confidence: 99%

“…The spinning motion induces a swirling flow towards the disk and is balanced by a radial outward mass flow, referred to as the von Kármán's viscous pump [22]. In a previous paper we reported on the interaction between dissolution, precipitation, and settling as it affects the formation of complex microstructures in the system AleW [23]. In this paper we develop a model that can explain the evolution of the microstructure in the presence and absence of electric and gravitational fields.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Dissolution and precipitation under gravitational conditions in the W–Al system

Unuvar¹,

Fredrick²,

Anselmi‐Tamburini³

et al. 2007

Intermetallics

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Dissolution and precipitation under gravitational conditions in the W–Al system

Unuvar¹,

Fredrick²,

Anselmi‐Tamburini³

et al. 2007

Intermetallics

Self Cite

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“…The method of combustion synthesis under the UHG field is being researched widely by material researchers. 13,14) The adiabatic temperature T ad analysis plays an important role in thermodynamic studies on combustion synthesis. [15][16][17][18] Firstly, the adiabatic temperature is a crucial variable governing the possibility of a self-sustainable reaction.…”

Section: Introductionmentioning

confidence: 99%

Predicting the Adiabatic Temperature of Transparent Y3Al5O12 Prepared via Combustion Synthesis under Ultra-High Gravity

et al. 2010

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In this paper, the adiabatic temperature of a transparent yttrium aluminum garnet (YAG) preparation using a NiO/Al/Y 2 O 3 aluminothermic system was calculated based on a thermodynamic theory. The results show that the adiabatic temperature without preheating reaches the 2891 K, which is higher than the melting points of YAG and Ni. The liquid phase mixture products can be separated and densified under ultra-high gravity (UHG). In the preheating temperature range of 620 K$2790 K to the reactants of this system, the adiabatic temperature is the same as 3156 K, the boiling point of Ni products. The theoretical analyses and experimental results prove the effectiveness of the YAG fabricated via combustion synthesis under an ultra-high gravity field.

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Transition from Impact‐induced Thermal Runaway to Prompt Mechanochemical Explosion in Nanoscaled Ni/Al Reactive Systems

Reeves

Mukasyan

Son

2013

Propellants Explo Pyrotec

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The effect of microstructure on ignition sensitivity and reaction behavior is investigated for nanoscaled Ni/Al gasless reactive systems. Nanometric homogeneity of the reactive media was achieved through (a) conventional mixing of nanometric powders; (b) short‐term high‐energy ball milling (HEBM) of micrometer‐sized powders. Sensitivity to thermal inputs is investigated by differential thermal analysis and mechanical sensitivity is studied by high‐rate shear impacts. The composite Ni/Al particles prepared by HEBM were extremely thermally sensitive, with reaction initiating at 220 °C, compared to 559 °C for nanometric powder samples and 640 °C for un‐milled, micrometer‐sized Ni+Al powder mixture. In contrast, nanometric powder mixtures were more susceptible to ignition through mechanical means, exhibiting a high‐speed reaction mode that is not observed in HEBM samples. The high‐speed mode preferentially appears in high‐shear regions and is interpreted as a mechanically‐induced thermal explosion. Its progression is tied to the passage of a stress wave in the heterogeneous media that heats and mixes the materials, rather than being propagated due to chemical energy release. The microstructures unique to each material are considered responsible for their individually ignition sensitivities. Specifically, the finely interspersed porosity in nanometric powder mixtures allows direct heating of the reactive interface between Ni and Al particles during compression through pore collapse and plastic deformation, which leads to exceptionally high mechanical sensitivity. The HEBM materials have high specific reactant interface area in the bulk of each composite particle that enhances thermal sensitivity, but the relatively low specific interface area between particles is unfavorable to mechanical ignition.

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Gravity effects on reactive settling in the Al–W system in SHS

Cited by 13 publications

References 23 publications

Dissolution and precipitation under gravitational conditions in the W–Al system

Dissolution and precipitation under gravitational conditions in the W–Al system

Predicting the Adiabatic Temperature of Transparent Y<SUB>3</SUB>Al<SUB>5</SUB>O<SUB>12</SUB> Prepared via Combustion Synthesis under Ultra-High Gravity

Transition from Impact‐induced Thermal Runaway to Prompt Mechanochemical Explosion in Nanoscaled Ni/Al Reactive Systems

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