[a] 1Introduction BPN is aw ell-knownp yrotechnic composition for ignition purposes. It has ah igh energy content and long shelf life. BPN containsb oron as fuel,p otassium nitrate as oxidizer, and polyester resina sb inder.H igh energy of the composition is due to boron, which has ah igh gravimetric (59 kJ kg À1 )a nd volumetric energy content (140 kJ cm À3 ) compared with the other fuels [1,2].B ut boron has ignition and combustion difficulty caused by the oxide layer formation (B 2 O 3 )o ni ts outers urface.T he melting point of the oxide layer is lower than the melting point of the core boron particle, whichi s450 8Ca nd 2077 8Ca t1 .013 10 5 Pa, respectively [3].T he oxide shell melts much before the solid core duringp article heating and ad iffusion-controlled process is initiated through the molten shell [4].I n order to increase ignition and combustion ability of boron, alternative solutionss uch as using nanometer-sized boron particles [5] or coating with materials having lower ignition temperature [6,7] were studied by different researchers.Young et al.[5] investigated the combustionc haracteristics of single boronp articles in nanometer size. He compared results with those of micrometer-sized particles studied in the past. Ignition and burning time characteristics of nanometer-sized boron particles were studied in the post flame region of af lat flame burner.T he first-stage and the second-stagec ombustion intervalswere analyzed and compared with the past studies of Yeha nd Kuo [8] performed on micrometer-sizedb oron particles. At lower temperatures, the second-stageb urning time was longer.Adirect linear relation between particle size and burning time for kinetic controlledc ombustion was observed. But the benefit in the first-stage burning time was not as high as expected when the particle sizew as reduced from 2-3 mmt o 200 nanometers range.Yetter et al.[9] reviewedt he classifications of metal combustion on the basis of thermodynamic considerations and different types of combustion regimeso fm etal particles. They thought that nanometer-sized energeticp articles have numerous characteristics thata re attractive for fuels and energeticm aterials. The majority of the highly desirable features of nanometer-sized metalp owders in combustion systemsw ere attributed to the high specific surface area and potential energy-storagea bility of such powders. The combustion rates of materials in nanometer size were found to increases ignificantly compared with those of similar materials in micrometer size.One of the recents tudies conductedb yY ang et al.[10] revealed the effect of particle size and pressure on the reactivity and kinetics of boron oxidation. The results indicat- Abstract:T he effect of micro-and nanometer-sized boron particles on boron-potassium nitrate (BPN) ignition composition was investigated in this paper.A sastartingp oint, thermochemicalc alculations were madet od eterminet he most promisingi gnition compositions. Both stoichiometric and fuel-richf ormulations of BPN were produced t...

No abstract

No abstract

Increasing insensitivity demands on initiation trains in missile systems necessitates utilizing high voltage initiators. Exploding Foil Initiator (EFI), also known as SlapperDetonator, is the well-known high voltage detonator that can only be initiated under the action of large electrical currents. EFI is strictly immune to Electrostatic Discharge (ESD), Electromagnetic Interference (EMI) and Radio Frequency Interference (RFI) effects due to its specific high current pulse need. Besides, an EFI can detonate a durable secondary high explosive like HNS-IV which is compliant to MIL -STD -1316. This paper mentions the effects of barrel length, bridge copper thickness and flyer plate thickness on the electrical performances of EFI striplines and average velocities of flyer plates experimentally. Furthermore, a numerical study is performed, which both predicts the electrical performances of EFI striplines and average velocities of flyer plates under specified parameters to have a better view of the integrity between theoretical and experimental results. NomenclatureA = constant for velocity calculations C = capacitance of the capacitor in Capacitor Discharge Circuit (CDC) C p = specific heat capacity CF = constant for velocity calculations E = energy I = time dependent current L = inductance L cdc = inductance of Capacitor Discharge Circuit (CDC) L sl = inductance of EFI stripline L t = total Inductance of EFI System M b = mass of the metallic bridge M f = mass of the flyer plate M tamp = mass of the tamper n = polytropic gas exponent Q 0 = initial electrical charge P e = pressure pulse on the explosive R = resistance R b = resistance of bridge R b0 = initial bridge resistance R cdc = resistance of Capacitor Discharge Circuit (CDC) 2 R cvr = resistance of Current Viewing Resistor (CVR) R d = total dynamic resistance of EFI System R sl = resistance of stripline R sw = resistance of spark gap switch R t = total resistance of EFI System T = temperature t = time t p = duration of the pressure pulse T 0 = initial temperature T b = burst temperature V = discharge voltage V 0 = initial voltage of the capacitor V f = final velocity of the flyer plate α = first temperature coefficient of resistance χ = displacement of the flyer plate = velocity of the flyer plate = acceleration of the flyer plate

No abstract