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Abstract:Composite explosives are the final energy source of energetic materials in realizing damage effect of weapons. In this paper, we briefly reviewed the recent advances and development trends in research of composite explosives, the advances of composite explosives aimed at higher energy are elaborated by the application of novel high explosives, energetic binders and plasticizers, and highly active metals, and then those formulations aimed at low sensitivity are introduced by the application of energetic materials inherent with low sensitivity, efficient desensitization technology, materials and microstructures for the resistance of stress and thermal environment. The composition, characteristics and application of typical explosive formulations are summarized based on different functions design. Finally, we proposed that the development directions of composite explosives in the future are pursuing higher energy, to be more insensitive, enhanced environmental adaptability, green explosives and improved theoretical design.

Abstract:To research the operating characteristics of high-speed ramjet kinetic energy projectile during the process of self-ignition, the process of self-ignition of high-speed ramjet kinetic energy projectile based on the solid fuel of polyethylene was numerically simulated. The ignition delay time in the self-ignition, the change law of flow field in combustor before the blanking cap opening, and the change law of flow field and performance of the entire ramjet after the flame in combustor stabilizing when the blanking cap opening were analyzed. Results show that because of its initial unique structure whose exit of nozzle is blocking, the ignition delay time is short enough, so the self-ignition can be successfully performed. Violent oscillation of pressure is occurred in the combustion chamber before the blanking cap opening, and chemical reaction in the combustion chamber enhances the effects of oscillation. After the blanking cap opening and flame in combustor stabilizing, the high-speed ramjet kinetic energy projectile′s rated thrust is 283 N and its net thrust is 83 N. The specific impulse based on polyethylene is 9129 m·s^-1.

Abstract:In order to understand the structural reliability of the solid rocket warhead in transport, the frequency domain method is used to evaluate the fatigue damage degree. The simplified kinetic model of the rocket launcher was built and the base excitation PSD (power spectrum density) of the charge was calculated by the transfer function and road load PSD; the finite element model of the charge was established and dynamic responses were solved by mode superposition methods; the fatigue damage degree was evaluated by Steinberg′s 3-σ Law. Results show that the random vibration of the warhead charge causes the dynamic stress, and the inner face of the top hole is the danger place with the stress peak value of 4.86 MPa. When the loading time reaches 250 h the damage degree is 1.12, which reveals that the warhead charge has been broken. The road roughness load can bring about the fatigue damage of the warhead charge, which has negative impacts on the structural reliability.

Abstract:To investigate the effects of charged particles (H₃O⁺, OH^-, NO₂⁺ and NO⁺) on the dissociation channel of 1, 1-diamino-2, 2-dinitroethylene (FOX-7), the complexes of H₃O⁺, OH^-, NO₂⁺ and NO⁺ respectively with FOX-7 were optimized using B3LYP, B3PW91 and PBE0 functional theory of density functional theory in 6-31++G (d, p) basis sets. The composite mode was analyzed from bonding styles and electrostatic potential. At the same level, the activation energies of the different dissociation channels of the complexes were calculated, and the nature of change in activation energies were analyzed based on the changes of the electronic structure parameters such as bond length, bond order and bonding styles. Results show that at B3LYP/6-31++G (d, p) level, OH^- makes the dissociation energies of the two configurations of C—NH₂ bond decrease by 260.6 kJ·mol^-1 and 74.3 kJ·mol^-1, respectively. H₃O⁺, NO₂⁺ and NO⁺ make the dissociation energies of C—NO₂ bond decrease by 44-260 kJ·mol^-1. The charged particles make the dissociation energy of C—C bond of the most complexes increase, but have little effect on the activation energy of nitro isomerism. By the analysis of the transition state, ones may know that this is due to the extremely similar geometry of the transition state of the nitro isomerism. The four kinds of charged particles disturb the relatively stable structure of FOX-7, reduce the energy barrier of the subsequent dissociation, and affect the self-acceleration reaction process in the late stage of FOX-7 dissociation.

Abstract:To select the energetic plasticizer which is compatible with 3, 3-bis (azido methyl) oxetane (BAMO) and tetrahydroxyl furan (THF) copolymer (PBT) and has low glass-transition temperatures of the mixture with PBT, the compatibilities between PBT and five kinds of energetic plasticizers, triethyleneglycol dinitrate (TEGDN), 1, 3-diazido-2-ethyl-2-nitropropane (DAENP), N-butyl nitroxyethyl nitramine (Bu-NENA), 1-allyl-3, 4-dinitropyrazole (ADNP), bis (2, 2-dinitropropyl) formal and bis (2, 2-dinitropropyl) formal acetal mixture (mass ratio of BDNPF/A is 1:1, A3), and glass-transition temperatures of PBT plasticizer blends were simulated and studied by means of MD method. The reasons of the interaction between PBT binder and energetic plasticizer were analyzed. Results show that the compatibility order of PBT and energetic plasticizer is Bu-NENA > DAENP > A3 > TEGDN > ANDP, TEGDN and ANDP are incompatible with PBT. The order of glass transition temperatures of the PBT and plasticizer mixture is PBT/Bu-NENA < PBT/TEGDN < PBT/DAENP < PBT/ADNP < PBT/A3. The compatibility between Bu-NENA and DAENP and PBT is better compared with the existing PBT plasticizer A3 and the glass transition temperatures of the PBT/Bu-NENA and PBT/DAENP mixed system are lower

Abstract:In order to study combustion performance of deterrent coated granular propellant and slotted stick propellant with constant volume, 7/19 propellants and 9/19 stick propellants were prepared by coating polymeric flame TiO₂. The closed-bomb tests of slotted stick propellant and deterrent coated propellant were carried out, and combustion performance of deterrent coated propellant and mixed charge with constant volume was investigated. The influence of mixed ratio of slotted stick propellant and deterrent coated propellant in different loading densities on combustion was studied. Combustion mechanism of slotted stick propellant and deterrent coated propellant was analyzed. The results show that loading density impacted the combustion of mixed charge, the higher loading density can increase burning progressivity and decrease erosive combustion. In this experiment, the suitable mixed ratio of slotted stick propellant and deterrent coated granular propellant is 4:6 and 3:7 when loading density is 0.20 g·cm^-3 and 0.32 g·cm^-3, which can lead to a good combustion progressivity. It was also found that slotted stick propellants and deterrent coated propellants interact seriously in the early stages of combustion.However, as the combustion progresses, the interaction between them gradually weakens.

Abstract:To explore the possibility of 3, 4-dinitropyrazole (DNP) instead of TNT as a new carrier for melt-cast explosives., its structure was characterized by optical microscope, FTIR spectrometer, UV VIS spectrophotometer, TG/DTA thermal analysis instrument. The heat of detonation and detonation velocity of DNP were respectively tested by an oxygen bomb calorimeter and the electrical measuring method. The detonation property parameters of DNP/CL-20 and TNT/CL-20 composite explosives were calculated by the VLW program. Results show that thermal decomposition of DNP, can be divided into two stages: ring′s breaking、nitro′s falling off from the ring of DNP and autocatalytic reaction.The apparent activation energy of thermal decomposition of DNP is 131 kJ·mol^-1. The experimental values of heat of detonation and detonation velocity of DNP are 4326 kJ·kg^-1 and 7633 m·s^-1, respectively. The detonation performances of DNP/CL-20 composite explosive are better than those of TNT/CL-20 composite explosive. The calculated values of detonation pressure and detonation velocity of DNP/CL-20 mixed explosive are 39.4 GPa and 8961 m·s^-1, respectively when DNP/CL-20=2:3(mass ratio).

Abstract:The reaction between the end hydroxyl of poly (glycidyl nitrate)(PGN) and isocyanates is easily affected by ambient moisture, and the curing stability is poor. Aiming at these problems, epoxy-terminated poly (glycidyl nitrate) (e-PGN) was synthesized. Its structure was characterized by infrared spectroscopy (IR), nuclear magnetic resonance (NMR) and gel permeation chromotagraph (GPC), and its major physiochemical properties were tested. The main physical properties of e-PGN, such as glass transition temperature, viscosity, density, thermal decomposition temperature, were close to those of PGN. The curing reactions of e-PGN with epoxy curing agents, such as imidazole (IMD), o-phthalic anhydride (PA), n-ethylethylenediamine (NEED) and isophorone diamine (IPDA) were studied. Results show that the curing reaction of e-PGN with IMD, PA, NEED and IPDA at 60 ℃/70 ℃ can be performed. When PA is used as curing agent, the mechanical properties of the cured material outperformed; the tensile strength is 0.912 MPa, and the elongation at break is 354%. In addition, the mechanical properties of the cured samples stored at room temperature for 8 months remained almost unchanged.

Abstract:To improve the bulk density and fluidity of nitroguanidine (NQ), spherical NQ crystal was prepared by spray crystallization method using N-methyl pyrrolidone as the solvent of NQ, anhydrous ethanol as a nonsolvent, nickel nitrate as crystal control agent. The optimal processing conditions of preparing high bulk density spherical NQ determined by single factor method were room temperature, volume ratio of solvent and nonsolvent of 1:10; mass fraction of the crystal control agent, spray pressure, bounce frequency and stirring speed were 0.5%, 0.6 MPa, 40 Hz and 450 r·min^-1, respectively; when spray finished, ultrasonic vibration should be continued for another 20 min. The optimal spherical NQ was analyzed by standard container method, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The results show that the prepared NQ is spherical and the bulk density is 1.232 g·cm^-3, which is improved by 0.943 g·cm^-3 compared with raw material NQ, decomposition temperature determined by DSC is 258.71 ℃, which is improved by 8.03 ℃ compared with that of raw material NQ.

Abstract:To reduce the electrostatic sensitivity of α-AlH₃, α-AlH₃ was coated by the solvent-nonsolvent method using stearic acid (SA) as coating material. The crystal structure and morphology of samples before and after coating were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), elemental analysis and scanning electron microscopy (SEM). The electrostatic sensitivity of α-AlH₃ samples before and after coating was measured by JGY-50Ⅲ type static spark sensitivity tester according to GJB5891.27-2006 method. Results show that a complete, uniform coating layer of SA is formed on the surface of α-AlH₃. The crystal structure and morphology of the sample after coating are not changed. When the spark energy required for 50% initiation probability (E₅₀) decreases from 367 mJ before coating to test limit 5390 mJ, the fire does not occur. The coating makes the electrostatic sensitivity reduce.

Abstract:To study the effect of eccentric initiation ways on the fragment dispersion rule of prismatic aimable warhead, the fragment dispersion velocity and fragment direction angle of prismatic aimable warhead in eccentric one line initiation on face, eccentric two lines initiation on face, eccentric three lines initiation on face, eccentric one line initiation on arris and eccentric two lines initiation on arris were simulated and studied by LS-DYNA software. The results show that the eccentric initiation can significantly improve the fragment velocity within the directional region. And the fragment beam is basically distributed in the radial direction of about 25°. When two eccentric lines on the arris detonate synchronously, the gain in fragment maximum dispersion velocity in the direction of the target can reach 29.73%. Using eccentric two lines sequential delay initiation on arris, it can make the axial direction angle change up to 6.77°.

Abstract:To obtain the initiation respone rule of explosive compound under the action of plasma, the plasma initiation experiments of explosive compound were performed using electrical exploding of nickel-chromium (Ni-Cr) and tungsten (W) wires as a plasma generating source, the voltage and current of plasma were measured by oscilloscope, and whether explosive detonation was judged by witness plates. Results show that the ability of octogen (HMX) initiated by Ni-Cr wire plasma is stronger than that of HMX nitiated by W wire plasma. When the initiation of HMX with particle size of 140 μm and 21 μm and of 10% charge density difference is selected, and lower charge density and smaller particle size are used, the plasma initiation respone of HMX is more intense. HMX, 1, 1-diamino-2, 2-dinitroethylene (FOX-7), N-guanylureadinitramide (FOX-12), 2, 6-diamino-3, 5-dinitropyrazine-1-oxide (LLM-105) and triaminotrinitrobenzene (TATB) can be initiated by plasma. 2, 4-dinitroanisole (DNAN) is ignited by heat of electrical exploding wire. The order of Ni-Cr wire plasma initiation sensitivity is HMX>LLM-105≈FOX7>FOX-12>TATB. The mechanism of explosive initiated by plasma is inferred as mixed initiation mechanism. A particles combustion model based on plasma is proposed.

Abstract:Halogenated adamantine derivatives are widely applied in the field of medicinal chemist, polymer and energetic materials as organic chemical intermediates. This review is intended to provide the synthetic methods of halogenated adamantine compounds, including 1-fluoroadamantane, 1-chloroadamantane, 1, 3, 5, 7-tetrachloroadamantane, 3-chloroadamantane-1-carboxylic acid, 3, 5-dichloroadamantane-1-carboxylic acid, octachloroadamantane-1-carboxylic acid, 1-bromoadamantane, 1, 3-dibromoadamantane, 1, 3, 5, 7-tetrabromoadamantane, 1-iodoadamantane and 1, 3, 5, 7-tetraiodoadamantane. It is worthy of further research, which includes the purification and separation process of polyhaloadamantane, new synthesis routes of halogenated adamantine with more than eight halogen atomes and new green reagents and catalysts.

Abstract:2, 4, 6-trinitrotoluene/2, 4, 6-trinitrochlorobenzene (TNT/TNCB) cocrystal explosive was prepared by cocrystallization in solution, and its crystal structure was characterized by single crystal X-ray. Results show that the crystal crystallizes is in monoclinic system, space groupP2₁/c with crystal parameters of a=2.1148(5) nm, b=0.60974(14) nm, c=1.4968(4) nm, α=90°, β=110.374(4)°, γ=90°, V=1.8093(7) nm³, Z=4. The thermal property and impact sensitivity of the product were measured by differential scanning calorimetry and sensitivity test, respectively. Results reveal that the melting point of TNT/TNCB cocrystal explosive is 72.7 ℃ and theH₅₀ of the cocrystal is 92.9 cm, which are lower than those of TNT and TNCB. Furthermore, the detonation velocity and pressure of TNT/TNCB cocrystal explosive were also calculated to be 7508 m·s^-1 and 24.52 GPa by density functional theory (DFT) and Kamlet-Jacobs equation.

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