Abstract:To research the micro-scale combustion characteristics of base bleed propellant ammonium perchlorate/hydroxyl terminated polybutadiene (AP/HTPB) under spinning condition, a two-dimensional periodic sandwich steady rotating combustion model of AP/HTPB was established. The gas phase adopts the two-step total reaction, coupled the gas-solid heat boundary layer, fitted the spinning momentum, and the two-dimensional flame structure under the conditions of combustion pressure of 0.1-5.0 MPa and spinning speed of 0-10800 r·min^-1 were numerically simulated. Results show that under the working condition of spinning speed as 10200 r·min^-1 when the combustion pressure is 0.1-0.5 MPa, the flame shows premixed combustion characteristics. When the combustion pressure is 0.5-3.5 MPa, the flame presents the dual characteristics of diffusion and premixed combustion. When the pressure is more than 3.5 MPa, a narrow diffusion chemical reaction zone is formed. The numerical analysis is carried out on steady combustion process at different combustion pressures and different spinning speeds. It is found that the deflecting angle of gas flame is linearly positive with the pressure. When the spinning speed is between 0-10200 r·min^-1, deflecting angle and spinning speed of gas flame show a linear increase. However, when the spinning speed is between 10200-10800 r·min^-1, the deflection angle of gas flame approximately shows an exponential growth with the spinning speed. The variation trend of the average Reynolds number of the combustion surface is basically the same as deflecting angle of the gas flame. Therefore, the average Reynolds number of the combustion surface can be used to describe the influence of the spinning and pressure on the deflecting angle of the gas phase flame.

Abstract:To explore the application possibilities of polyglycidyl nitrate plasticizer (PGNN) in propellants and PBX explosives, a series of PGNN with different number average molecular weight were synthesized. The relationships between molecular weight and density, viscosity, glass transition temperature and volatility were studied. The compatibility of PGNN with the main components of propellants and explosives were investigated by TG, and the hazard during storage and transportation were studied by sensitivity test and transport vibration test. Results show that PGNN with molecular weight of 523 has a higher density (1.43 g·cm^-3), lower glass transition temperature (-56 ℃) and lower volatility (60 ℃, 0.096 mg·cm^-2·h^-1). PGNN is compatible with HMX, RDX, AP and Al etc., and has good safety characteristics. Both the friction sensitivity and the impact sensitivity are 0, and no combustion or explosion occurs during the 4 hours of simulated highway transportation test. This research reveals that PGNN with molecular weight of about 500 is an ideal oligomer plasticizer.

Abstract:To realize the deformation field measurement of mixed mode crack tip and failure mode analysis of hydroxyl-terminated polybutadiene (HTPB) propellant, HTPB propellant specimens with central through-mixed mode cracks were made. Tensile observation test was carried out. The propagation characteristics of the mixed mode crack were obtained. Digital image correlation(DIC) method was used to obtain the strain field on the surface of the specimen and the crack tip. The characteristics of the strain field near the mixed mode crack tip and the relationship between the strain field and the crack propagation law were studied. The results show that the tensile process of mixed mode crack specimens can be divided into three stages: linear segment, nonlinear segment and failure segment, and the crack propagates in the direction perpendicular to the load. The digital image correlation method using large deformation analysis method can effectively solve the problem of large deformation of the specimen, and can quantitatively give the strain field on the surface of the specimen and the strain concentration area is consistent with the theoretical results. The expansion of mixed mode cracks is closely related to the change of the strain field. The strain field generates strain concentration at the crack tip, leading in crack propagation.

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Abstract:To reduce the energy consumption and avoid the secondary contaminants caused by the use of additives during unsymmetrical dimethylhydrazine (UDMH) wastewater treatment, a kind of TiO₂ nanorod array (NRAs)/CdS/Au thin film photocatalyst with visible light response was prepared. Results show that TiO₂ NRAs/CdS/Au composite film can degrade UDMH using visible light, and when using the simulated sun light as light source. the degrading effect of composite film on UDMH was better that of composite film on UDMH when using the pure visible light as light source. The degradation rate of UDMH decreases gradually along with the increase of initial concentration of UDMH, but the total degradation concentration increases. The suitable pH for the photocatalytic degradation of UDMH wastewater by TiO₂ NRAs/CdS/Au composite film is about 7.2. Addition of hole-capture scavenger, hydroxyl radical scavenger and pumping nitrogen gas all make the degradation rate of UDMH decrease, while pumping air makes the degradation rate of UDMH increase. The TiO₂ NRAs/CdS/Au composite film can degrade the toxic substances, nitrosyldimethylamine (NDMA) and formaldehyde dimethylhydrazone (FDMH), which are produced during the degradation of UDMH when the irradiation of simulated sunlight and visible light respectively, but the degradation effect of the simulated sunlight is better and pumping ozone can help the rapid removal of NDMA and FDMH.

Abstract:To determine the reaction pathway of unsym-dimethylhydrazine (UDMH) to nitrosodimethylamine (NDMA) in the atmosphere, the reaction mechanism of UDMH oxidation to NDMA in the atmosphere was studied using quantum chemical method. The geometric configuration optimization and frequency calculation of reactants, intermediates, transition states and products of the reaction system were carried out at B3LYP/6-311+G(d,p) and M06-2X/6-311+G(d,p) levels. The single points energies of the species were corrected at the CCSD(T)/aug-cc-pVTZ level and the potential energy surface profile for the reactions was constructed. Results show that the oxidation initiation of UDMH is a dehydrogenation or oxygenation process. Considering the concentration of oxidants in the atmosphere, the ratio of reaction rate of UDMH initiated by different oxidants is: v(O₃)≈10⁴×v(HO·)≈10⁸ ×v(O₂) .The oxidation of UDMH is mainly trigged by ozone, forming (CH₃)₂NNH(IM1) after the removal of hydrogen atoms. Then IM1 can be converted into NDMA under the action of HO·, HO₂·, O₃ in the atmosphere environment. Ozone participation in the process will reduce the activation energy of the reaction and promote the formation of NDMA in the atmosphere.

Abstract:N,N"-Bis(fluorodinitroethyl)-3,4-diamino furazan (LLM-208) was nitrated using the nitration system of 98% fuming nitric acid/acetic anhydride (10∶8 in volume) at 0 ℃. N,N′-bis(2-fluoro-2,2′-dinitroethyl)-3,4-dinitraminefurazan (LLM-209) was prepared from LLM-208. The single crystal of LLM-209 was obtained by volatilization culture in anhydrous methanol. The single crystal structure was measured by X-ray single crystal diffractometer. The thermal decomposition of LLM-209 was studied by thermogravimetry and differential scanning calorimeter（TG-DSC）. The gaseous products of thermal decomposition of LLM-209 were measured by TG-IR. The detonation velocity and detonation presure of LLM-209 were predicted by EXPLO5(V6.02) program. Its impact and friction sensitivities were measured by sensitivity test.Results show that the crystal of LLM-209 belongs to the monoclinic system, space group P2₁/n, and its density at 298 K is 1.94 g·cm^-3. LLM-209 has a melting endothermic peak at 94.27 ℃ and two distinct decomposition exothermic peaks at 179.96 ℃ and 233.86 ℃. The gaseous products of thermal decomposition of LLM-209 are mainly NO₂，CO₂，CO and N₂O. The theoretical detonation velocity and detonation presure of LLM-209 are 8981 km·s^-1 and 40.3 GPa, respectively, and the impact and friction sensitivities are 4 J and 48 N, respectively.

Abstract:To research the synthesis and performances of energetic compounds of bisisoxazole, three kinds of energetic compounds with low melting point, 5,5′-bis(azidomethyl)-3,3′-biisoxazole(2), [3,3′-biisoxazole]-5,5′-diylbis-(methylene)dinitrate(4) and [3,3′-biisoxazole]-4,4′,5,5′-tetrayl-tetrakis(methylene) tetranitrate(6) were synthesized via [3+2] cyclization reaction, nitration and azidation, using dichloroglyoxime, alkynol and propargyl bromide as starting materials, with a yield of 66%, 67% and 64%, respectively, and the structures of target compounds and intermediates were characterized by the means of IR, NMR and elemental analysis. The reaction mechanism of constructing bisisoxazole through two reactions of —C⁺ N—O^- and CC with 1,3-dipolar cycloaddition was discussed. The thermal behavior of compounds （2）, （4） and （6） were studied by DSC and TG. The melting temperature of compounds （2）, （4） and （6） are 77.46, 95.18 ℃ and 124.36 ℃. The starting temperature of thermal decomposition are 179.21, 165.34 ℃ and 168.69 ℃, respectively.

Abstract:Nano-1,1-diamino-2,2-dinitroethylene(FOX-7) was prepared by the solvent-non-solvent method using N,N-dimethylacetamide(DMAC), N-methylpyrrolidone (NMP) and a mixture of the two as solvents. The morphology, phase, structure and thermal performances of the prepared nano-FOX-7 were characterized by field emission scanning electron microscope (FE-SEM), X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FT-IR), differential scanning calorimetry(DSC) and thermogravimetric analysis(TG) method and its sensitivities were tested. On this basis, the effects of solvents and surfactants on the performances of nano-FOX-7 were investigated The results show that the average grain size of the prepared nano-FOX-7 is less than 30 nm. The addition of surfactant is helpful to reduce the grain size and particle size of the prepared nano-FOX-7, enhance its uniformity of particle size distribution and improve its dispersity. Compared with the raw material, the initial decomposition temperatures of the prepared nano-FOX-7 increase, the temperature ranges between their two decomposition exothermic peaks become narrow, their energy release efficiency and decomposition enthalpy greatly increase and the impact and friction sensitivities significantly reduce. When using the mixed solvents and adding the surfactants OP-10 and Tween 20, the initial decomposition temperatures of the prepared nano-FOX-7 increase nearly by 15 ℃, the enthalpies of decomposition increase by 4.97% and 4.65% respectively. And the friction sensitivities decrease by 66.7% and 50.0% respectively.

Abstract:To further improve the forming effect of suspended explosive ink, a kind of "O/W" type binder emulsion was designed by using ethyl acetate solution of type 26 fluoroelastomer (Viton) as oil phase, aqueous solution of polyvinyl alcohol (PVA) as water phase, Tween-80 and sodium dodecyl sulfate (SDS) as surfactants. The orthogonal design of L₂₅(5⁶) was designed by SPSS data analysis software. The content of each component and preparation process in emulsion were optimized. The analyzed and optimized results were verified by experiments, and the stability of emulsion was evaluated by the static stability of emulsion as index. The microstructure of emulsion was measured by optical microscope. The suspended explosive ink was prepared using emulsion as binder system，hexanitrohexaazaisowurtzitane(CL-20) as the body explosive. The direct writing pattern and crystal type of the explosive ink were analyzed. The results show that the mass ratio of Tween-80/SDS is 1∶2, The mass fraction of an emulsifier (the total mass of the emulsion) is 2%, the concentration ratio of water phase to oil phase is 2∶1, the stirring time is 30 min, the emulsifying temperature is 20 ℃ and the stirring speed is 350 rpm, are more conducive to maintaining the stability of binder emulsion. The emulsion binder system prepared by optimized experimental conditions can be stable about 360 h. The size of dispersed phase droplet in the emulsion is 20-120 μm, the distribution is uniform and there is no obvious agglomeration phenomenon. The prepared explosive ink writes smoothly without blocking the direct writing needle and the crystal type of CL-20 in explosive ink composite has no change.

Abstract:To investigate the influence rule of quasi-isentropic loading characteristics on the initiation response characteristics of polymer bonded explosive (PBX), the initiation response process of PBXC03 explosive under quasi-isentropic loadings with different loading pressures(8, 10, 12 GPa) and loading slopes was numerically simulated. The parameters of an elastic/viscoplastic double hollow spherical-shell collapse reaction rate model (DZK) of PBXC03 explosive were determined by backside particle-velocity history curves at 1, 1.5, 2, 3 mm and 4 mm obtained from the initiation response experiment of PBXC03 explosive under the quasi-isentropic loading. The influence rule of peak pressures and loading slope on the initiation response characteristics of PBXC03 explosive under quasi-isentropic loadings was obtained by the DZK model and the parameters. The results show that the two loading methods(different pressures and loading slopes) have a great influence on the initiation process of PBXC03 explosive. Under other conditions being equal, the higher the loading slope or peak pressure is, the faster the growth of peak pressure curve and the shock wave trace of shock wave front in the explosive, and the shorter the time-detonation is.

Abstract:To accurately establish the strength criterion of TATB-based PBX materials, the strength data under different confining pressures (0-10 MPa) and different temperatures (22.5, 35, 50 ℃) were obtained through the self-developed active confining pressure tester. Based on the experimental data of uniaxial tension, uniaxial compression and confining pressure compression, traditional Drucker-Prager（D-P） and hyperbolic D-P strength criteria were used to establish the strength model of TATB-based PBX at different temperatures, and the prediction accuracy for experimental strength data was analyzed. Results show that the maximum relative errors of the hyperbolic D-P strength criterion at 22.5, 35 ℃ and 50 ℃ are 2.41%, 3.46% and 5.22%, respectively, and the root mean square errors are 0.42, 0.38 MPa, and 0.44 MPa, respectively, which are better than those of the traditional D-P strength criterion. The relative errors for the prediction of indirect triaxial tensile and compressive failure stress are 4.93% and 12.14% respectively and they are superior to the traditional D-P, Mohr-Column, twin shear and uniaxial strength criteria. The hyperbolic D-P strength criterion of considering the influence of middle principal stress and being everywhere regular, can accurately predict the strength characteristics of TATB-based PBX materials at different temperatures.

Abstract:From three aspects of metal foil bridge electrical explosion, electrical explosion drive flyer and flyer shock initiation explosive, the research progress in the function mechanism of exploding foil initiators was reviewed. It is considered that the exploding foil initiators have made important progress in the sectional resistivity model, advanced flyer velocity measurement technology, calculation model of the electrical explosion drive flyer velocity based on the energy conversion coefficient and the sensitivity prediction based on the critical initiation criterion etc aspects. Some regular knowledges have been obtained and the low energy design is promoted to some extent. It is pointed out that the quantitative description of energy dissipation and flyer ablation, temporal shape of the flyer in the flight, non-ideal detonation performance prediction at small scale and the micro reaction flow observation technology after the wave front will become the key points in the future research of exploding foil initiators in the electrical explosion drive flyer process under the small size condition.

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