Pyrophoricity of nascent and passivated aluminum particles at nano-scales

Sundaram, Dilip Srinivas; Puri, Puneesh; Yang, Vigor

doi:10.1016/j.combustflame.2013.03.031

Cited by 36 publications

(18 citation statements)

References 20 publications

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“…Based on a free-molecular heat transfer model, nascent aluminum particles smaller than 32 nm were predicted to be pyrophoric. Reasonably good agreement with experimental data was achieved [57]. The continuum model, however, significantly overestimated heat losses to the ambient gas; the resulting critical particle size was 18 nm.…”

Section: Deficiencies Of Continuum Modelssupporting

confidence: 55%

“…Sundaram et al [57] studied pyrophoricity of nano aluminum particles in air at a pressure of 1 atm, based on a transient energy balance analysis. The study considered conduction and radiation heat losses to the ambient gas.…”

Section: Deficiencies Of Continuum Modelsmentioning

confidence: 99%

“…At nano scales, the energy release could be sufficient to ignite the particle due to its low volumetric heat capacity. The critical particle size below which aluminum particles are pyrophoric is 32 nm [57]. Therefore, great care must be taken when handling nano aluminum particles.…”

Section: Introductionmentioning

confidence: 99%

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Combustion of nano aluminum particles (Review)

Sundaram

Yang

Зарко

2015

Combust Explos Shock Waves

280

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Nano aluminum particles have received considerable attention in the combustion community; their physicochemical properties are quite favorable as compared with those of their micron-sized counterparts. The present work provides a comprehensive review of recent advances in the field of combustion of nano aluminum particles. The effect of the Knudsen number on heat and mass transfer properties of particles is first examined. Deficiencies of the currently available continuum models for combustion of nano aluminum particles are highlighted. Key physicochemical processes of particle combustion are identified and their respective time scales are compared to determine the combustion mechanisms for different particle sizes and pressures. Experimental data from several sources are gathered to elucidate the effect of the particle size on the flame temperature of aluminum particles. The flame structure and the combustion modes of aluminum particles are examined for wide ranges of pressures, particle sizes, and oxidizers. Key mechanisms that dictate the combustion behaviors are discussed. Measured burning times of nano aluminum particles are surveyed. The effects of the pressure, temperature, particle size, and type and concentration of the oxidizer on the burning time are discussed. A new correlation for the burning time of nano aluminum particles is established. Major outstanding issues to be addressed in the future work are identified.

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Section: Deficiencies Of Continuum Modelssupporting

confidence: 55%

Section: Deficiencies Of Continuum Modelsmentioning

confidence: 99%

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Combustion of nano aluminum particles (Review)

Sundaram

Yang

Зарко

2015

Combust Explos Shock Waves

280

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“…Studies have been focused on the effects of particle properties [10] and external factors [11] on the reaction. For example, Sundaram et al [12] found that the freshly prepared aluminum powder was extremely active and could undergo spontaneous oxidation reactions in any oxidizing environment. As the reaction proceeded, the oxidation produced an oxide film on the particle surface, which passivated the aluminum particles.…”

Section: Introductionmentioning

confidence: 99%

Effects of Moisture Content on the Minimum Explosible Concentration of Aluminum Powder and the Related Mechanism

et al. 2020

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Aluminum powder has been widely applied to various industries. However, its high activity and high burn rate can cause serious explosion risks. Many factors affecting the explosion of aluminum powder have been determined, yet moisture content has not been included. In the present work, the minimum explosible concentrations of aluminum powders with different moisture contents were measured with a 20-liter explosion test apparatus using the explosion accident in Kunshan, China, as a study case. The experimental results suggest that the minimum explosible concentration of aluminum powder dramatically increases with the increase of its moisture content first and the increasing trend becomes slower as the moisture content further increased. The oxidation time has no significant effects on the minimum explosible concentration of aluminum power in 8 hours at room temperature. Further investigation suggests that the moisture lowers the explosion risk of aluminum powder by altering its surface oxide film, ignition, and combustion process. The low contents of moisture in the range of 0%-8% increase the minimum explosible concentration of aluminum powder by inhibiting the reaction kinetics and particle agglomeration, while high contents of moistures in the range of 8%-20% affect the minimum explosible concentration by the endothermic effect and oxygen dilution effect.

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“…Being pyrophoric, their MIE is zero and their MIT is below ambient temperature. Whether pyrophoricity occurs in practice depends on a heat balance involving factors like exothermicity of the oxidation reaction, particle size, thickness of oxide layer, and boiling points of metal and oxide relative to adiabatic flame temperature 75,76) . The pyrophoric nature of fine powders of reactive metal, especially those in the nano range, complicates testing procedures to determine explosion indexes, requiring modification of standard dust explosion testing equipment and procedures for explosion severity 77) and explosion sensitivity 78) .…”

Section: Effects Of Reducing Particle Size Towards the Size Of Molecumentioning

confidence: 99%

A Review of the Fire and Explosion Hazards of Particulates

Lemkowitz

Pasman

2014

KONA

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Particulate fires and explosions cause substantial loss of life and property. With the goal of understanding, preventing, or at least mitigating particulate fire and explosion hazards, we review basics. We distinguish between 'hazard' and 'risk' and discuss the fire and explosion hazards of particulates, the many factors determining such hazards, hazard indexes, and ways to reduce fire and explosion hazards. While our primary goal is to improve safety, we briefly discuss how fundamental knowledge can be extracted from weapon technology based on particulate combustion. We review the prevention of and protection against particulate explosions and discuss ongoing and future research.

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Pyrophoricity of nascent and passivated aluminum particles at nano-scales

Cited by 36 publications

References 20 publications

Combustion of nano aluminum particles (Review)

Combustion of nano aluminum particles (Review)

Effects of Moisture Content on the Minimum Explosible Concentration of Aluminum Powder and the Related Mechanism

A Review of the Fire and Explosion Hazards of Particulates

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