Shock compression of reactive powder mixtures

Eakins, Daniel E.; Thadhani, Naresh N.

doi:10.1179/174328009x461050

Cited by 95 publications

(41 citation statements)

References 123 publications

(268 reference statements)

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“…The lack of a predictive understanding of these materials leads to their underutilization and therefore significant effort is being dedicated to characterizing and modeling these reactions. 1 Two distinct modes for reaction upon impact have been identified, shock-assisted and shock-induced chemical reactions. 6 Shock-assisted reactions occur in the period of thermal equilibration typically well after the shock wave has passed.…”

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confidence: 99%

“…1,7 However, nanoscale reactive composites are significantly more sensitive to impact and thermal ignition and have faster reaction rates than mixtures using micron size powders due to higher surface areas and smaller diffusion distances. 2,8,9 It has also been observed that higher bulk densities can lower impact ignition thresholds in nano mixtures.…”

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confidence: 99%

“…Their potential use as structural energetic materials, as enhanced blast materials and for the synthesis of novel metastable non-equilibrium materials has driven research focused on their mechanical impact behavior. [1][2][3] Numerous experimental and theoretical studies have been published on impact behavior and shock compression of metal-based reactive powder mixtures with metals such as Al, Ni, Si, Ti, W, Nb, and more. [1][2][3][4][5] Yet the fundamental mechanisms that govern the initiation and front propagation are not well understood.…”

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confidence: 99%

“…[1][2][3] Numerous experimental and theoretical studies have been published on impact behavior and shock compression of metal-based reactive powder mixtures with metals such as Al, Ni, Si, Ti, W, Nb, and more. [1][2][3][4][5] Yet the fundamental mechanisms that govern the initiation and front propagation are not well understood. For example, their energy release characteristics depend on the mode of initiation, and reaction propagation, in a currently unpredictable way.…”

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The role of microstructure refinement on the impact ignition and combustion behavior of mechanically activated Ni/Al reactive composites

Mason

Groven

Son

2013

Journal of Applied Physics

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Metal-based reactive composites have great potential as energetic materials due to their high energy densities and potential uses as structural energetic materials and enhanced blast materials however these materials can be difficult to ignite with typical particle size ranges. Recent work has shown that mechanical activation of reactive powders increases their ignition sensitivity, yet it is not fully understood how the role of microstructure refinement due to the duration of mechanical activation will influence the impact ignition and combustion behavior of these materials. In this work, impact ignition and combustion behavior of compacted mechanically activated Ni/Al reactive powder were studied using a modified Asay shear impact experiment where properties such as the impact ignition threshold, ignition delay time, and combustion velocity were identified as a function of milling time. It was found that the mechanical impact ignition threshold decreases from an impact energy of greater than 500 J to an impact energy of $50 J as the dry milling time increases. The largest jump in sensitivity was between the dry milling times of 25% of critical reaction milling time (t cr ) (4.25 min) and 50% t cr (8.5 min) corresponding to the time at which nanolaminate structures begin to form during the mechanical activation process. Differential scanning calorimetry analysis indicates that this jump in the sensitivity to thermal and mechanical impact is dictated by the formation of nanolaminate structures, which reduce the temperature needed to begin the dissolution of nickel into aluminum. It was shown that a milling time of 50%-75% t cr may be near optimal when taking into account both the increased ignition sensitivity of mechanical activated Ni/Al and potential loss in reaction energy for longer milling times. Ignition delays due to the formation of hotspots ranged from 1.2 to 6.5 ms and were observed to be in the same range for all milling times considered less than t cr . Combustion velocities ranged from 20-23 cm/s for thermally ignited samples and from 25-31 cm/s for impacted samples at an impact energy of 200-250 J.

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The role of microstructure refinement on the impact ignition and combustion behavior of mechanically activated Ni/Al reactive composites

Mason

Groven

Son

2013

Journal of Applied Physics

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“…The high exothermic energy release inherent in the reaction pathways of the Ti/B system in particular is postulated to promote combustion in Al powders by enhancing localization phenomena and mixing in powder compacts. The reactive behavior in these systems under shock loading or high strain rates depends largely on extrinsic properties such as microstructural distribution and constituent size/morphology, as well as intrinsic physical properties such as particle hardness and surface reactivity [1,2,3,4,5]. The crucial elements necessary for impact-induced reaction initiation in heterogeneous systems however remain unknown.…”

Section: Introductionmentioning

confidence: 99%

Meso-scale simulations of strain-induced reaction mechanisms in Ti/Al/B heterogeneous systems

Gonzales¹,

Gurumurthy²,

Gokhale³

et al. 2012

AIP Conference Proceedings

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High‐Pressure Methods in Solid‐State Chemistry

Huppertz

Heymann

Schwarz

et al. 2017

Handbook of Solid State Chemistry

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Solid‐state chemistry exhibits an intriguing variety of methods for the syntheses of new materials. The majority of these methods deal with variations of the reactive compounds including an enhancement of the temperature. The latter factor provides the reactions with the essential kinetic energy as one of the most important factors for a successful solid‐state synthesis. An alternative or additional route to supply the synthesis of solids with the necessary reaction energy is the use of high pressures. Technically, this way is much more demanding due to the fact that the stabilization of such extreme conditions requires sophisticated devices. This chapter will introduce into the main techniques of high‐pressure solid‐state chemistry giving a brief overview of the assets and drawbacks of each method. Additionally, the main principles of high‐pressure chemistry are explained including a chapter of recent advances in the field of high‐pressure solid‐state chemistry.

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Shock compression of reactive powder mixtures

Cited by 95 publications

References 123 publications

The role of microstructure refinement on the impact ignition and combustion behavior of mechanically activated Ni/Al reactive composites

The role of microstructure refinement on the impact ignition and combustion behavior of mechanically activated Ni/Al reactive composites

Meso-scale simulations of strain-induced reaction mechanisms in Ti/Al/B heterogeneous systems

High‐Pressure Methods in Solid‐State Chemistry

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