Characterization of BPN Pyrotechnic Composition Containing Micro‐ and Nanometer‐Sized Boron Particles

Koc, Suzan; Ulaş, Abdullah; Yilmaz, Nil Ezgi Dinçer

doi:10.1002/prep.201400255

Cited by 10 publications

(8 citation statements)

References 10 publications

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“…Because of its high gravimetric and volumetric energy density, boron is attractive as a fuel for propellants, − explosives, and pyrotechnics . However, relatively low reaction rates impede its use in many energetic formulations. , In order to modify boron to achieve higher reaction rates, its ignition and combustion mechanisms must be understood and described quantitatively.…”

Section: Introductionmentioning

confidence: 99%

Reactive Shell Model for Boron Oxidation

et al. 2019

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An approach suitable for quantitative description of oxidation of porous powders with a complex particle morphology is developed and applied for a 95% pure boron powder. It is shown that boron particles, which are agglomerates of nanosized, partially fused primary particles, can be represented as spheres with reactive porous shells and impenetrable cores. The oxidation of such powders is assumed to occur volumetrically within the reactive shells. The shell thickness is obtained from simple experiments with the actual powders. To determine the thickness, thermo-gravimetric measurements are performed and processed for powders with different but overlapping particle size distributions. The processing uses measured powder particle size distributions to assign fractions of the powder mass gain to individual particle size bins. Selection of the appropriate initial reactive shell thickness makes it possible to ensure that particles of the same size present in samples with different size distributions oxidize in the same way. The specific powder studied here was successfully described with a reactive shell thickness of about 1.28 μm. Surface area measurements can be used to interpret the reactive shell as comprising packed spherical primary particles. For the powder used here, the radius of such primary particles is 80 nm. The proposed reactive shell model is shown to be valid as long as the thickness of boron oxide grown on the primary particles does not exceed 15 nm. The approach is useful for describing reactions leading to ignition of porous powders and of powders consisting of irregular aggregates in particular. It is also expected to be applicable to describe corrosion, catalyst aging, and other phenomena involving surface reactions for such powders.

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Section: Introductionmentioning

confidence: 99%

Reactive Shell Model for Boron Oxidation

et al. 2019

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“…Aluminum (Al) powder and boron (B) powder are widely used as the metal fuel in the field of propellant and explosives [1][2][3][4]. Although Al powder has a high energy density, there're still some defects in the combustion of Al powder: The solid alumina film on the surface of aluminum particles causes long ignition delay and slow burning rate.…”

Section: Introductionmentioning

confidence: 99%

“…For example, the ignition temperature of the Al powder can be effectively reduced and the ignition delay can be shortened by adding Li and Mg element to the Al powder [13][14][15][16]. Shoshin [17] prepared a metastable AlÀTi alloy powder by a mechanical milling method and found that the formation of the metastable phase Al 3 Ti triggered the combustion of the AlÀTi alloy powder when heating the AlÀTi alloy powder. Fu Hao [18] found the formation of intermediate phase Al 4 Eu by melting europium (Eu) element into Al powder changes the internal structure of the particles, thereby increasing the oxidation reactivity of the Al powder.…”

Section: Introductionmentioning

confidence: 99%

The Oxidation and Combustion Properties of Gas Atomized Aluminum−Boron−Europium Alloy Powders

Wang

Zou

Cai

2019

Propellants Explo Pyrotec

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In this paper, the Aluminum−boron−europium ternary alloy fuels with boron content of 1.5∼4.85 wt. % and europium content of 3 wt. % were prepared by the close‐coupled gas atomization. XRD, SEM, TG‐DTA and oxygen bomb test were used to analyze the phase constituents, morphology, thermal oxidation behavior and combustion exothermic property of powders, respectively. The functions of boron and europium on the combustion of metal fuels were studied, and a reasonable oxidation model of the alloy particles was proposed. The results show that there are Al, AlB2, Al4Eu and B6Eu in the alloy. When the europium content is constant, the combustion enthalpy of the Al−B−Eu alloy powder firstly increases and then decreases as the boron content increases. Additionally, at oxygen pressure of 3.0 MPa, the Al−3.5B−3Eu ternary alloy powder burned completely with the maximum combustion enthalpy of 33324.5 J g−1. This increases by 11 % compared with theoretical combustion enthalpy of aluminum powder (31.1 kJ g−1). Al−3.5B−3Eu undergoes a dramatic oxidation exothermal phenomenon at 1110 °C with the weight increase efficiency of 53.66 %, which is 1.7 times that of aluminum. Due to the synergistic effects between the phase of B6Eu and AlB2 inside the alloy particles, the Al−3.5B−3Eu alloy powder shows excellent exothermic performance.

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“…Pyrotechnics are typically fuel‐rich because they can take oxygen from the atmosphere to provide more heat release. Research also shows that fuel‐rich BPN performs better than that of the stoichiometric material composition . Therefore, oxygen balance was calculated for an initial selection of the formula, as shown in Table .…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, the use of boron leads to high output energy of BPN. In addition, BPN possesses desirable properties, such as long shelf life and usage safety [2]. When applied in energetic materials, amorphous boron is preferred due to its high specific area and high reaction activity.…”

Section: Introductionmentioning

confidence: 99%

Ignition and Combustion Behavior of Sintered‐B/MgB₂ Combined with KNO₃

Sun

Ren

Jiao

et al. 2020

Propellants Explo Pyrotec

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To further enhance the performance of B/KNO 3 (BPN) igniter, sintered B/MgB 2 (s-B/MgB 2 ) powder was proposed to be used as a boron substitute. The amount of heat release was tested by oxygen bomb and thermogravimetry/differential scanning calorimetry (TG/DSC). s-B/ MgB 2 /KNO 3 (sBPN) igniter could not release as much heat as BPN igniter in the oxygen bomb due to the reduced calorific value of the s-B/MgB 2 . However, calculations show that s-B/MgB 2 reached an over 90 % heat release efficiency in oxygen bomb, compared to that of 53.34 % for boron. At heating rate of 10 K min À 1 in TG/DSC experiment, 19.5 % sBPN (sBPN with 19.5 wt. % s-B/MgB 2 powder) has a heat release of 1815 J g À 1 and experienced an exothermic span of 2.10 min, whereas it took 24.5 % BPN (BPN with 24.5 wt. % boron powder) 3.45 min to release 1465 J g À 1 . The pressuretime curve (P-t curve), burning rate and combustion tem-perature were determined. The P-t curve indicates that the combustion pressure was more readily established with the sBPN than with the BPN. The maximum pressure rise of sBPN was 362.0 Pa ms À 1 , whereas the figure for BPN is 77.2 Pa ms À 1 . Coupled with infrared radiation (IR) temperature thermometer, the distribution of the flame temperature field during combustion was obtained. It is shown that the combustion temperature of 19.5 % sBPN igniter is approximately 800 K higher than that of 24.5 % BPN. IR images of the combustion process show that the temperature difference of the 19.5 % sBPN flame is smaller than that of the 24.5 % BPN. 19.5 % sBPN also produces more hot residue, which contains KMgF 3 , resulting in a longer high-temperature duration. The higher combustion pressure and temperature and more residue may enable the sBPN to readily ignite the following charge.

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Characterization of BPN Pyrotechnic Composition Containing Micro‐ and Nanometer‐Sized Boron Particles

Cited by 10 publications

References 10 publications

Reactive Shell Model for Boron Oxidation

Reactive Shell Model for Boron Oxidation

The Oxidation and Combustion Properties of Gas Atomized Aluminum−Boron−Europium Alloy Powders

Ignition and Combustion Behavior of Sintered‐B/MgB₂ Combined with KNO₃

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Characterization of BPN Pyrotechnic Composition Containing Micro‐ and Nanometer‐Sized Boron Particles

Cited by 10 publications

References 10 publications

Reactive Shell Model for Boron Oxidation

Reactive Shell Model for Boron Oxidation

The Oxidation and Combustion Properties of Gas Atomized Aluminum−Boron−Europium Alloy Powders

Ignition and Combustion Behavior of Sintered‐B/MgB2 Combined with KNO3

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Ignition and Combustion Behavior of Sintered‐B/MgB₂ Combined with KNO₃