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Abstract:In recent years, energetic metal-organic frameworks(E-MOFs) have received worldwide research attention due to their promising characteristics of both high energy level and low sensitivity. The design and syntheses of new E-MOFs with new structures, high energy level and excellent safety property have become a research hotspot in the field of energetic materials. Up to now, the energetic organic ligands that have been used for the construction of E-MOFs can be classified into three major categories: small molecular energetic ligands (azide anion and hydrazine), nitrogen-rich heterocyclic ligands (triazole, tetrazole and derivative), energetic ligands with multiple explosophores (e.g. nitro group). According to above classification of three energetic ligands, in this paper, we briefly reviewed the recent advances of E-MOFs from the standpoints of their self-assembly strategies, energy level, and safety issues. After systemically analyzing above advances in the field of E-MOFs, it can be conclude that the rational design and selection of nitrogen-rich multbentate energetic ligand molecules and their self-assembly metal ions are the key to successfully construct novel E-MOFs, since different self-assembly methods will determine the topologies of the E-MOFs′networks and thereby significantly influence the physicochemical properties of the resulting E-MOFs. As a newly emerging class of energetic materials, E-MOFs have exhibited unique properties including high energy level and low sensitivity, demonstrating the important research value and development potential among the applications of solid propellant formulations and laser initiation fields.

Abstract:To study the anti-penetration performance of composite armor with aluminum foam, based on the stress-wave propagation characteristics, a theorytical analysis of the structure of ceramic/aluminum foam/aluminum alloy composite armor was carried out. The energy absorption rule, residual velocity of jet head, and protective capability of armor under different dip angle were investigated from three aspects of different aluminum foam sandwich thickness, different thickness and arrangement way of front-back plate under the composite armor with same thickness, and composite armor dip angle. Results show that the aluminum foam as sandwich layer can reduce the particle velocity of back plate of composite armor adequately. Under the same dip angle θ, the particle velocity of back plate decreases with increasing thickness of aluminum foam. When the thickness of foam aluminum is 2.4 mm, the residual velocity of the jet head is minimum, the energy of the composite armor is maximum and the anti-penetration performance is optimal. Under the same thickness of aluminum foam, with increasing the thickness ratio t₁/t₂, the residual velocity of jet head of the interval and contact type composite armor decreases firstly, and then increases. When t₁/t₂=1, the anti-penetration performance of interval type composite armor is optimal. When the layout way is not the same only, the difference of penetration performance between interval and contact type composite armor is small. With increasing the dip angle θ, the protective capability of composite armor increases firstly, and then decreases. When the dip angle θ is 20°, the anti-jet penetration performance of composite armor is optimal.

Abstract:Aiming at the applied problem in underwater munitions of explosively formed projectile(EFP) warhead, the rule of velocity attenuation, mass loss and penetration ability against spaced targets under different distance conditions of EFP in water was simulated and studied by the LS-DYNA finite element software. The test verification was carried out by a high-speed photography. Results show that the configuration of EFP after entering water is unstable. The mass of EFP is sharply decreased, even leads to fragmentation. With increasing the traveling distance of EFP in water, the mass of EFP is reduced to 1/3~1/5 of initial mass. The velocity of EFP in water decreases linearly at first and then decays exponentially. The EFP of traveling the 2.5 times charge diameter distance can penetrate the 5 mm target plate, but the EFP of traveling the 5 times more than charge diameter distance has no penetration ability.

Abstract:In order to obtain overpressure distribution of moving cloud detonation, process of cloud dipersion and detonation was surveyed by airdrop. A high-peedmotion analyzer system and a pressure measurement system were used to measure process of cloud detonation and pressure field during explosion. Fuel dispersion and overpressure field were studied. The variation of blast parameters with propagation distance for non-stiffener structure and stiffener structure was analyzed. Results show the maxium value of peak overpressure for detonation with non-stiffenerstructure is 3.62 MPa, and with stiffener structure is 3.20 MPa. Detonation of non-stiffenerstructure has great damage range. Peak overpressure of detonation increased 31.2% with the same dose for static detonation. Mutilate distance for detonation is larger than static detonation.

Abstract:To investigate the influences of aluminum size and content on the performance of aluminized explosives in confined space, experiments were conducted in a fully confined chamber. Two kinds of RDX based explosives with different aluminum oxygen ratio(0.45 and 0.99) containing aluminum of 50 nm, 5 μm and 50 μm respectively were used. The data processing method of multipoints averaging for gaining quasic-static pressure and exponential decay similar for gaining the attenuation factor of pressure were proposed. Three characteristic quantities, quasic-static pressure (p_QS), rising time of pressure (t_QS) and attenuation factor of pressure (ω), were used to characterize the energy release from aluminized explosives in chamber. Results show that for the formulation with aluminum oxygen ratio of 0.45, the p_QS of sample with 50 μm aluminum powder is 0.3% and 0.7% higher than those with 5 μm and 50 nm aluminum, respectively. For the formulation with aluminum oxygen ratio of 0.99, the p_QS of sample containing 50 μm aluminum powder was 31.2% and 31.9% higher than those containing 5 μm and 50 nm aluminum powder, respectively, and the p_QS of two samples with aluminum oxygen ratio of 0.45 containing the same particle size aluminum powder are larger than the sample with aluminum oxygen ratio of 0.45. With respect to either samples containing the same size of aluminum, with the increase of aluminum oxygen ratio, p_QS increased, t_QS and ω decreased.

Abstract:To improve the crystal morphology of 2, 6-diamino-3, 5-dinitropyrazine-1-oxide(LLM-105) and control the crystal size distribution of LLM-105, the metastable zone width of LLM-105 in dimethyl sulfoxide(DMSO) was measured by turbidity method using a CrystalSCAN multi channel crystallization instrument. The effects of initial concentration, stirring speed and cooling rate on the metastable zone width were studied. The nucleation orders effected by cooling rate were calculated based on the classical nucleation theory. Results show that in the cooling crystallization process, the metastable zone width of LLM-105 in DMSO narrows with increasing the initial concentration and stirring speed. The metastable zone width broadens with increasing the cooling rate. The optimal crystallization conditions obtained are initial concentration of 0.0700 g·mL^-1, stir speed of 390 r·min^-1 cooling rate of 1.0 ℃·min^-1. The nucleation order increases from 1.825 to 2.5747 when the initial concentration increases from 0.0670 g·mL^-1 to 0.0750 g·mL^-1. Under the optimal crysallization conditions, the controllable high quality LLM-105 columnar particles with smooth surface, ruly morphology and particle size of 60 μm are obtained by adding the 2.5 g LLM-105 crystal seed with particle size of 4 μm into DMSO-LLM-105 solution.

Abstract:2, 6-Bis(picrylamino)-3, 5-dinitropyrazine(BPNP), a new energetic compound, was synthesized with a total yield of 47% from 2, 4, 6-trinitrochlorobenzene and 2, 6-diaminopyrazine via condensation and nitration. The structure of BPNP was characterized by infrared(IR) spectroscopy, nuclear magnetic resonance(NMR) and mass spectrometer(MS). The yield of condensation was the highest, while the optimal solvent was isopropanol and the optimal catalyst was pyridine. The effect of the nitrition was the best, while the volume ratio between H₂SO₄ and HNO₃, reaction temperature and reaction time were V(H₂SO₄):V(HNO₃)=4:1, 50 ℃ and 3 h, respectively. The decomposition temperature of BPNP is 374.3 ℃, which was investigated by thermogravimetry(TG) and differential scanning calorimetry(DSC). The theoretical density of BPNP after optimizing predicted by Monte-Carlo method is 1.82 g·cm^-3. The detonation velocity and detonation pressure predicted by Kamlet-Jacobs formula are 8.13 km·s ^-1 and 28.25 GPa. H₅₀ of impact sensitivity predicted by electrostatic potential is 83 cm. All the results show that BPNP has higher detonation pressure than PYX, and has potential value in application and research.

Abstract:An energetic plasticizer 4, 4, 4-trinitrobutyric acid 2-azido-1-azidomethyl-ethyl ester(DPTB) was synthesized via esterification reaction from 4, 4, 4-trinitrobutyric acid(TNB)and 1, 3-diazido-propan-2-ol(DAG), in which, TNB was prepared via nitration-hydrolysis and addition reaction using 4, 6-dihydropyrimidine as raw material, and DAG was prepared via azidation by 1, 3-dichloro-propan-2-ol as raw material. The structure of DPTB was characterized by IR, NMR and elemental analyses. In synthesis, traditional esterification method was replaced by dicyclohexylcarbodiimide(DCC)/dimethylaminopyridinium p-toluenesulfonate(DPTS) catalytic esterification method. The effects of material ratio, reaction temperature, reaction time and solvent dosage on the esterification reaction were investigated. The thermal decomposition properties of DPTB were studied by thermogravimetry(TG) and differential scanning calorimetry(DSC). Results shw that replacing traditional esterification method with DCC/DPTS catalytic esterification method makes the yield of DPTB promote from 17.9% to 44.9%.There are two exothermic peaks at 215 ℃ and 230 ℃ on DSC curve of DPTB. Its TG curve can be divided into two stages: first-stage is from147 ℃ to 220 ℃ accompanied with 76.68% mass loss; second-sstage is from 220 ℃ to 351 ℃ accompanied with 15.23% mass loss and the total mass loss from start to the end of decomposition reaction is 91.19%.

Abstract:Using anhydrous hydrazine and trimethyl chlorosilane as raw materials, 1, 2-bis(trimethylsilyl)hydrazine was synthesized with the yield of 83%. Then through activation of butyllithium, tris(trimethylsilyl)hydrazine were synthesized with the total yield of 75%. Further through solvothermal reaction of lithium-tris(trimethylsilyl)hydrazine and trimethyl chlorosilane, tetra(trimethylsilyl)hydrazine were synthesized with the total yield of 34%. Their structures were characterized by means of NMR, IR, MS and elemental analysis. The self-condensation reaction of mono(trimethylsilyl)hydrazine and rearrangement reaction of bis(trimethylsilyl)hydrazine induced by heat action were analyzed. Results show that these reactions are caused by the inter-and intra-molecular migration of trimethylsilyl group on hydrazine, and isomerization of bis(trimethylsilyl)hydrazine could occur obove 75 ℃.

Abstract:3-Cyano-4-nitrofuroxan was synthesized from dicyanopropane via diazotisation, addition, cyclization and oxidation reactions, and its structure was characterized by IR, ¹³C NMR and ¹⁵N NMR and elemental analysis. The yields of cyclization and oxidation reactions are 55.1% and 83.6%, respectively. In the ¹³C NMR, the chemical shifts were assigned by comparing with 3-cyano-4-nitrofurazan, which further confirm the configuration of 3-cyano-4-nitrofuroxan. The bond order, density, enthalpy of formation and detonation parameters of 3-cyano-4-nitrofuroxan were calculated theoretically. Results show that the minimum bond order are N(1)—O(4)(0.84) and C(6)—N(9) (0.91), the density is up to 1.74 g·cm^-3, the enthalpy of formation is 352.6 kJ·mol^-1, and the detonation velocity and detonation pressure are 8352 m·s^-1 and 30.9 GPa, respectively.

Abstract:To study the problem of detonation and effect for suspended aluminum dust, the development propagation process of detonation wave for suspended aluminum dust with a concentration of 0.304 kg·m^-3 for the equivalence ratio of aluminum dust and air as 1 and a radius of 2.0 μm for the aluminum particles in the space connected by channel were numerically investigated by the two-phase flow model. The ignition initiation of detonation wave and the pressure and temperature distribution of the propagation, reflection and diffraction processes of detonation wave were achieved by numerical simulation. Results show that the detonation wave is reflected at the wall to form a 6.5 MPa local high pressure zone in the left side of enclosed space in simulated area, whereas the interaction of detonation wave with the reflected waves generated by the two walls can form a local high pressure zone of 18 MPa. Through diffraction, the detonation wave can propagate into the channel and reach the speed of 1571 m·s^-1 and the pressure of 2.85 MPa near the exit of channel, closing to the stable propagation state. Through diffraction, the detonation wave can propagate into the right side of space and form a symmetrical low-pressure low-density area at the exit of the channel, the pressure of detonation wave and detonation velocity decrease, continue to spread in the right side of space. The temperature of the most of the region behind detonation wave in calculation area remains above 3400 K.

Abstract:To safely and accurately monitor the risk of combustion and explosion of explosive and propelant powder caused by electrostatic discharge, aiming at three kinds of monitoring methods, including field strength monitoring and Faraday cylinder charge quantity monitoring and induced current integral charge quantity monitoring, corresponding testing devices were established. The contrast testing study on the accuracy of the electrostatic field monitoring data obtained by different methods and the reliability of the electrostatic monitoring was performed by the way of substitute material and the safety of the monitoring system was evaluated. Results show that when powder pile height in storage bin is 200 mm, the field strength monitored by powder pile surface is 2160 kV, which is only 1/7 of the field strength of 14709 kV in base of powder pile, when powder pile height is 100 mm, the field strength data of powder pile surface is 20 times of the calibration data, it can not achieve accurate and reliable monitoring of electrostatic discharge risk. The monitoring data of Faraday cylinder charge quantity monitoring method and induced current integral charge quantity monitoring method are accurate, they can realie the reliable monitoring of electrostatic field, but Faraday cylinder charge quantity monitoring system itself exists the risk of electrostatic discharge, whereas induced current integral charge quantity monitoring system has good safety.

Abstract:To investigate the effect of potassium chloride(KCl) on the detonation performance and thermal stability of ammonium nitrate(AN), modified AN containing KCl was prepared via, solution mixing method and mechanical mixing method. The detonation performance and thermal stability of AN/KCl mixtures were investigated by differential scanning calorimetry(DSC), accelerating rate calorimeter(ARC), the United Nations(UN) gap test and Koenen test. Results show that the exothermic peak temperature of modified AN containing 10% KCl obtained by solution mixing method was decreased from 286.75 ℃ to 250.84 ℃, while the onset temperature of modified AN was increased from 204.33 ℃ to 220.17 ℃, revealing that KCl can promote the thermal decomposition process of AN and doesn't affect first step of the thermal decomposition of AN. The detonation test results show that KCl can reduce the thermal sensitivity of AN and the detonation propagation ability to a certain extent. Compared with mechanical mixing method, to suppress the detonation of AN, the amount of KCl required can reduce by 20% for solution mixing method. The mixing method has an important effect on the detonation characteristics of AN.

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