Abstract:

Abstract:In order to study the damage of polymer bonded explosive（PBX） under dynamic shock loads， the constitutive curve of the mechanical damage of PBX under different strain rates was obtained by using the Split-Hopkinson pressure bar（SHPB） test device. And the constitutive parameters in the Z-W-T constitutive model with damage variables were fitted in sections. Then， based on the fitting results， the finite element theory， elastoplastic mechanics and ABAQUS/VUMAT， the subroutine of PBX containing damage is completed， and is verified by the finite element simulation. The model is used for finite element engineering examples. Results show that the verification results of finite element samples are in good agreement with the experimental results， and the correlation degree of the results is higher than 0.95.The stress cloud diagram and damage variable cloud diagram for fragment penetration example reflect the change and possible damage location of PBX under shock loads.The evolution process of damage cloud diagram reflects the correlation between damage evolution and strain rate effect of PBX.

Abstract:Nano-thermites， as one kind of energetic composites， have wide applications. A systematic study on the relationship between the interface structures and properties has great significance for the preparation of the new nano-thermites with excellent performance. The structures and energies of Fe₂O₃（104） and Fe₂O₃（110） surfaces and the structures， bonding properties， and adhesion work of Al（111）/Fe₂O₃（104） and Al（111）/Fe₂O₃（110） interfaces （AFS1， AFS2， AFS3， AFS4 and AFS5） were studied with the periodic density functional theory in this work. Results show that O-terminated Fe₂O₃（104） and Fe₂O₃（110） surfaces and the interfaces formed by these surfaces with Al（111） are more stable than those of the （104） and （110） surfaces of Fe₂O₃ respectively. Among 5 of the Al/Fe₂O₃ interfaces， the interfaces composed by the O-terminated Fe₂O₃（104） and Fe₂O₃（110） surfaces with Al（111）， i.e.， AFS1 and AFS5， have the maximum adhesion work （3.92 J·m^-2 and 3.02 J·m^-2， respectively）， and AFS1 is more stable than AFS5. In these two most stable interfaces， the Al atoms stack on the top position of the O atoms of the Fe₂O₃ surfaces and the binding of Al and Fe₂O₃ surfaces is mainly through the Al-O ionic bonds.

Abstract:Laminated composite charge is composed of two or more different charges by way of superposition， in which the safety and power performance can be regulated through the design of charge structure. To study the sympathetic detonation safety of laminated composite charge， typical composite charges which contain both the high energy charge and insensitive charge were selected as research objects. The effect of different charges structure on critical sympathetic detonation distance was explored through numerical simulation and sympathetic detonation tests. Results showed that， compared to simple high energy charge， the sympathetic detonation of composite charge decreases 53.3%（from 7.5 mm decreases to 3.5 mm）， while energy decreases 22.9%. The thickness of insensitive charge must reach a certain threshold（3 mm） in order to reduce the critical sympathetic detonation distance obviously. As the content of insensitive charge increases， the critical sympathetic detonation distance is closer to insensitive charge.

Abstract:To investigate the influence of temperature-induced phase transition of polytetrafluoroethylene （PTFE） on the fracture toughness of Al-PTFE reactive material， the quasi-static tensile test and fracture toughness test were performed， and the normalization data reduction technique with single specimen in ASTM E1820 was applied for analyzing the elastic-plastic fracture toughness of Al-PTFE by J-integral method. Combined with the microstructures analysis of the fracture surface， the effect of temperature on the fracture toughness of Al-PTFE was revealed. The results show that the strength of Al-PTFE reactive material decreases with the increase of temperature， while the fracture toughness increases. Moreover， the yield strength and fracture toughness of this material change obviously after crossing the phase transition temperature. The crack propagation pattern changes from brittle fracture to ductile fracture. Furthermore， when PTFE is in phase Ⅱ， less PTFE fibrils can be formed by stretching. However， increasing temperature can lead to the transform of the crystal phase for PTFE to phase Ⅳ and Ⅰ. Besides， the stable formed PTFE fibrils can effectively dissipate the external energy in the form of local plastic deformation. The crack tip is passivated by winding bridging， so as to prevent the crack propagation and improve the fracture toughness of this material.

Abstract:A novel energetic non-metallic pentazolate salt， 3，5-diamino-4-nitro-1H-pyrazol-2-ium pentazolate （3）， was synthesized by a metathesis reaction of 3，5-diamino-4-nitropyrazole hydrochloride with sodium pentazolate. The structure of 3 was characterized by nuclear magnetic resonance （NMR）， single crystal X-ray diffraction analysis （SC-XRD）， Fourier infrared spectroscopy （IR） and elemental analysis （EA）. The study on thermal behavior of 3 by using differential scanning calorimetry （DSC） and thermogravimetry （TG） show that its onset decomposition temperature is 119.5 ℃， which is higher than most non-metallic pentazolate salts. The apparent activation energies were calculated based on DSC curves at different heating rates. Based on the measured density at room temperature （1.71 g·cm^-3） and calculated enthalpy of formation （503.3 kJ·mol^-1）， the detonation performances of 3 （D=8483 m·s^-1， p=26.4 GPa） were calculated by Explo5 V6.05.02 software. The impact sensitivity and friction sensitivity of 3 are 10 J and 216 N， respectively.

Abstract:2，4-MDNI/DNTF eutectic system was prepared by using 1-methyl-2，4-dinitroimidazole （2，4-MDNI）， a high energy insensitive explosive， to improve the high sensitivity and high melting point of the dynamite carrier 3，4-dinitrofuroxan （DNTF）. The melting and liquefaction processes of 2，4-MDNI/DNTF with different ratios were studied by differential scanning calorimetry （DSC）， and the T-x phase diagram was established. The melting and decomposition processes of 2，4-MDNI， DNTF and 2，4-MDNI/DNTF eutectic at different heating rates were studied. The kinetic parameters of 2，4-MDNi， DNTF and their eutectic were calculated by flynn-wall-Ozawa method， Doyle method and Kissinger method respectively. XRD and SEM analysis were carried out for the three substances. The hyposensitivity of 2，4-MDNI to DNTF was studied by sensitivity test.The detonation properties of 2，4-MDNI/DNTF eutectic were calculated by using EXPLO5. The results show that the molar composition of 2，4-MDNI/DNTF eutectic is 51∶49， and the average melting point is 92.7 ℃. As the heating rate increases， both melting and decomposition reactions are delayed. The activation energy E_a and pre-exponential factor A of thermal decomposition of eutectic are 146.0 kJ·mol^-1 and 4.09×10¹³， respectively. In XRD test， the low eutectic of 2，4-MDNI/PETN generates a new diffraction peak at 2θ=18.60°. The microstructure of the solidified surface is obviously better than that of DNTF. The impact and friction sensitivities of 2，4-MDNI are both 0%.The impact sensitivity and friction sensitivity of eutectic are 64% and 52%， respectively. The theoretical density of 2，4-MDNI/DNTF eutectic is 1.844 g·cm^-3， and the calculated detonation velocity is 8705 m·s^-1. The eutectic of 2，4-MDNI and DNTF was prepared with ideal melting point and good thermal stability. At the same time， the sensitivity of DNTF can be significantly reduced while maintaining its high energy level.

Abstract:［1，2，5］ oxadiazole ［3，4-b］ pyrazine-5，6-（1H，3H）-dione（1） was synthesized directly from 3，4-diaminofurazan and oxalic acid by one-step amide condensation reaction， and the corresponding ionic salts 2-5 were further synthesized by reaction with base. The structures of compounds 1-5 were characterized by infrared spectrum （IR）， 1H and 13C nuclear magnetic resonance（NMR）. The structures of compounds 1 and 5 were further characterized by X-ray single crystal diffraction. The thermal behaviors of compounds 1-5 were investigated based on differential scanning calorimetry （DSC） measurement. The thermal decomposition temperatures of compounds 1-5 ranged from 210.5 ℃ to 313.5 ℃. The physicochemical properties and detonation performances of compounds 1-5 were estimated by Gaussian 09 program and Explo 5（v. 6.01）. The calculated detonation velocities of compounds 1-5 ranged from 7327 m·s^-1 to 8555 m·s^-1， and the detonation pressures ranged from 20.5 GPa to 30.6 GPa. The impact and friction sensitivities were determined by using BAM technology. The impact sensitivity of compound 1 is 27 J and the friction sensitivity is 280 N. The impact sensitivities of compounds 2-4 are all greater than 40 J and the friction sensitivities of 2-4 are 360 N. The impact sensitivity of sodium salt is 7 J and the friction sensitivity is 120 N. Among them， energetic salts 3 and 4 are expected to be new energetic materials with high energy and low sensitivity.

Abstract:In order to improve the low-temperature resistance of emulsion explosives （EE）， dimethyl sulfoxide （DMSO） was added into the aqueous phase of emulsion explosive matrix （EEM）. The crystallization rate， and microscopic structure and detonation performance of brisance of the prepared EEM were studied. And the thermal decomposition characteristics of EEM were also tested thermogravimetry-derivative thermogravimetry （TG-DTG） technology. The results show that adding 1.5% （mass fraction） of DMSO can delay the time for the EEM to reach the maximum crystallization rate from 24 days to 51 days under the condition of freezing at -20 ℃， compared to the EEM without DMSO. After being frozen for 12 days， the EEM containing DMSO has a more uniform distribution of emulsion particles. DMSO （1.5%） can increase the brisance of EE by 29.9%. The addition of DMSO has no obvious effect on the thermal decomposition process of EEM， but the apparent activation energy of EEM decreased with the increase of the DMSO content. When the DMSO content reached 1.5%， the apparent activation energy of EEM decreased by about 18.5%

Abstract:To investigate the thermal hazards of the synthetic reaction process of FOX-7， the heat flow curve of the hydrolysisinvolved therein has been measured by using Reaction Calorimeter （RC1）. The n^th-order kinetic models were applied to different temperature systems and the apparent kinetic parameters of these processes were obtained. The results indicated that the exothermic heat of the synthesis reaction was -46.563 kJ∙mol^-1， and the adiabatic temperature rise was 9.1 K. Under the thermal runaway chemical reaction condition， the maximum temperature of the synthesis reaction （MTSR） is 29.1 ℃. The reaction order is 1.21 for synthesis of 2-（dinitromethylene）-5，5-dinitrodihydropyrimidine-4，6-dione. The activation energy （E_a） of the reaction is 73.2 kJ∙mol^-1， with the pre-exponential factor of 5.03×10⁹ s^-1.

Abstract:In order to explore the thermal decomposition behavior of 3，5-dimethyl-4-hydroxyphenylpentazole， UV-visible light absorption spectrum combined with quantum chemical calculation was adopted. The thermal decomposition of 3，5-dimethyl-4-hydroxyphenylpentazole （HMPP） with increasing temperature was tracked. The thermal stability of HMPP was tested by differential scanning calorimeter. The results show that the initial decomposition temperature of HMPP is -14 ℃， and the characteristic absorption peak produced by the pentazole ring is at 284 nm in the UV-visible region. The characteristic absorption peak of 3，5-dimethyl-4-hydroxyphenyl azide （HMPA） is 258 nm. With the increase of temperature， the absorption peak of the whole system decreases gradually at 284 nm. In order to explore the specific reasons for the change of HMPP ultraviolet-visible light absorption spectrum， the decomposition products of HMPP were separated by column chromatography. The main decomposition products of HMPP were 2，6-dimethyl-p-benzoquinone and 4-（4-hydroxy-3，5-dimethylphenyl） amino）-2，6-dimethylcyclohexa-2，5-diene-1-one. After the thermal decomposition of HMPP， the uV-visible absorption of the whole system was determined to be caused by the superposition of uV-visible absorption of compounds 4 and 5.

Abstract:Metastable intermolecular composites （MICs） have the advantages of ultra-high reaction rate， high bulk energy density and micron critical reaction propagation size. They show broad application prospects in military fields such as micro energetic devices and rocket propellants. Nano Al/CuO energetic composite films are one of the research hotspots in the field of metastable intermolecular composites. They are prepared by vapor deposition， compatible with the micromachining process of energetic micro electro mechanical systems （MEMS）， and have great application prospects in integrated energetic devices. The preparation， thermal properties， combustion properties， reaction kinetics， the effect of transition layer on the properties of Nano Al/CuO energetic composite films， energetic devices （igniters） and their application technology are reviewed， and the development direction of Nano Al/CuO energetic composite films is prospected.

Abstract:Energy Coordination Compound （ECC） has become one of the research hotspots in recent years because of its diverse Coordination modes between different metal elements and ligands， and it is expected to obtain energetic materials with highly adjustable properties. In this paper， the ways and types of assembling ECC with different ligands are reviewed， and the applications of ECC and its functional materials as initiators， propellant catalysts， flammable agents and oxidants of thermite， pyrotechnics colorants are reviewed. Studies have shown that the energetic complexes formed after the coordination of different metal ions and nitrogen-rich ligands show great potential in the field of new energetic materials， and can meet the requirements of energy， sensitivity and other properties through the change of the type and number of ligands. The law of ECC synthesis is summarized and how to improve the energy characteristics and expand the application in the future is prospected.