Reaction Delay of Aluminum in Condensed Explosives

Chan, Sek Kwan

doi:10.1002/prep.201400093

Cited by 12 publications

(2 citation statements)

References 15 publications

(16 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…8,9 Aluminum is a high energy density fuel (i.e., heat of combustion equivalent to 30 372 J g À1 ) that is often incorporated into explosives and other energetic material systems. [10][11][12][13] For this reason, research on aluminum and iodine oxide reactions not only provides an understanding of fundamental reactivity directly representative of an application, but also often includes an analysis of the response of bacteria to exposure from the reaction. 2,8,9 While Al particles have the potential to provide great calorific energy, much of the chemical energy stored in a single particle is rarely fully exploited.…”

Section: Introductionmentioning

confidence: 99%

Effect of environment on iodine oxidation state and reactivity with aluminum

Smith

McCollum

Pantoya

2016

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

Iodine oxide is a highly reactive solid oxidizer and with its abundant generation of iodine gas during reaction, this oxidizer also shows great potential as a biocidal agent. A problem with using I2O5 in an energetic mixture is its highly variable reactive behavior. This study isolates the variable reactivity associated with I2O5 as a function of its chemical reaction in various environments. Specifically, aluminum fuel and iodine oxide powder are combined using a carrier fluid to aid intermixing. The carrier fluid is shown to significantly affect the oxidation state of iodine oxide, thereby affecting the reactivity of the mixture. Four carrier fluids were investigated ranging in polarity and water miscibility in increasing order from hexane < acetone < isopropanol < water as well as untreated, dry-mixed reactants. Oxidation state and reactivity were examined with experimental techniques including X-ray photoelectric spectroscopy (XPS) and differential scanning calorimetry (DSC). Results are compared with thermal equilibrium simulations. Flame speeds increased with polarity of the fluid used to intermix the powder and ranged from 180 to 1202 m s(-1). The I2O5 processed in the polar fluids formed hydrated states of iodine oxide: HIO3 and HI3O8; and, the nonpolar and dry-mixed samples formed: I2O4 and I4O9. During combustion, the hydrated iodine oxides rapidly dehydrated from HIO3 to HI3O8 and from HI3O8 to I2O5. Both steps release 25% of their mass as vapor during combustion. Increased gas generation enhances convective energy transport and accounts for the increase in reactivity seen in the mixtures processed in polar fluids. These results explain the chemical mechanisms underlying the variable reactivity of I2O5 that are a function of the oxide's highly reactive nature with its surrounding environment. These results will significantly impact the selection of carrier fluid in the synthesis approach for iodine containing reactive mixtures.

show abstract

Section: Introductionmentioning

confidence: 99%

Effect of environment on iodine oxidation state and reactivity with aluminum

Smith

McCollum

Pantoya

2016

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

show abstract

“…Conceptually, the rate of particle reaction is proportional to the exposed surface area, favouring use of the smallest particle available. The emphasis on particle size has been further reinforced by the inappropriate extension of measurements of single particle combustion in propellant environments to the condensed-phase detonation environment [5]. In single particle combustion, the particle is heated until ignition, at which point it burns until it is quenched or fully consumed.…”

Section: Introductionmentioning

confidence: 99%

Scaling of the propulsive capability of aluminized gelled nitromethane

Loiseau

Georges

Frost

et al. 2018

AIP Conference Proceedings

View full text Add to dashboard Cite

Small mass fractions (< 20%) of micron-scale aluminium particles added to a high explosive can react quickly and with sufficient exothermicity to improve metal-acceleration ability (AA) relative to an equal volume of only the base explosive. In order for the aluminium to increase AA, exothermicity must more than offset losses in gas-production and from heating and accelerating the solid particles in the flow. Furthermore, particles must react promptly to deliver this energy prior to loss in driving pressure from product expansion or acoustic decoupling from the driven material. For these reasons, many aluminized formulations exhibit slight or no increase in AA. Furthermore, AA is typically studied using the cylinder test, which specifies a fixed, heavy copper wall. In the present study the authors have used symmetric sandwiches of flyer plates of widely different thicknesses to examine how charge scaling and plate acceleration time-scales influence the enhancement in AA for different sizes of aluminium particles. Nitromethane gelled with 4% Poly(methyl methacrylate) by mass was used for the explosive. 3M K1 microballoons were added at a mass fraction of 0.5% to sensitize the mixture. Aluminium with a mean particle size of 3.5 µm or 108 µm was added at 15% total mixture mass fraction. At 15% mass fraction, an enhancement in AA was observed for both particle sizes and flyer configurations. Results indicated an onset of reaction close to the sonic plane of the detonation wave.

show abstract

Reaction of a Particle Suspension in a Rapidly‐Heated Oxidizing Gas

Soo

Goroshin

Bergthorson

et al. 2015

Propellants Explo Pyrotec

View full text Add to dashboard Cite

The reaction of a suspension of solid particles in a rapidly‐heated oxidizing gas is relevant to metalized explosives and propellants, as well as to combustion of solid fuel‐particle suspensions in premixed‐gaseous‐fuel clouds encountered in accidents within the mining and process industries. A simplified model is considered, using a constant‐volume approximation, which assumes that non‐volatile particles react heterogeneously via a one‐step surface reaction. The resulting unified particle reaction rate includes both kinetic and diffusive reaction resistances. It is shown that the onset of the chemical reaction in a rapidly heated particulate suspension may occur by two different physical mechanisms. The first mechanism, realized in a dilute suspension of particles, is defined by the ignition of a single particle, i.e., by the critical phenomenon associated with the rapid transition from a kinetically‐ to diffusively‐limited reaction regime. The second mechanism dominates the reaction onset in a dense particulate suspension and occurs in a similar manner to the reaction onset in a rapidly‐heated homogeneous gas mixture, where the highly‐activated reaction occurs in an explosion‐like manner after some time delay and preheating. Unlike the single particle ignition phenomenon, the second mechanism lacks criticality and is not limited to particles above a certain size. The interplay between these two reaction‐onset mechanisms leads to a nontrivial dependence of the total reaction time on the particle size and solid‐fuel concentration within the suspension.

show abstract

Reaction Delay of Aluminum in Condensed Explosives

Cited by 12 publications

References 15 publications

Effect of environment on iodine oxidation state and reactivity with aluminum

Effect of environment on iodine oxidation state and reactivity with aluminum

Scaling of the propulsive capability of aluminized gelled nitromethane

Reaction of a Particle Suspension in a Rapidly‐Heated Oxidizing Gas

Contact Info

Product

Resources

About