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Abstract:In order to study the detonation wave propagation characteristics of composite charge under eccentric initiation, the detonation wave was measured by the orthogonal multi-slit scanning technology.By analyzing geometric relation of multi-slits scanning traces from two mutually perpendicular directions, the detonation wave propagation velocity and direction at the intersection of multi-slits were obtained.Moreover, combined with the propagation process map of directional convergent detonation wave, the propagation characteristic of detonation wave was investigated.Results show that because of the difference between inner and outer charging detonation velocity, the detonation wave propagation is in an arc shape in the process of convergence inside, then forms a horn shaped wave, and the detonation velocity along the centerline increases by about 1.67 mm·μs^-1.

Abstract:The air explosion experiments were carried out to investigate the effects of content and size of titanium hydride(TiH₂) on properties of RDX-based TiH₂ composite explosive.Meanwhile, the solid explosion products were analyzed.Results show that the explosion properties of composite explosive are improved with decreasing of TiH₂ size.Compared to standard RDX, the peak overpressure, positive duration and positive impulse of composite explosive with TiH₂ content of 20% and size of 0.96 μm increase 3.8%, 12.7% and 14.0%, respectively.As the content of 0.96 μm TiH₂ increasing from 10% to 20%, the explosion positive impulse increases 7.0% and the peak overpressure decreases 5.1%.Variance analysis indicates that titanium hydride size has a significant impact on properties of composite explosive, and there was an interaction between titanium hydride content and size.Analysis of solid explosion products reveales that the TiH₂ is oxidized into TiO₂ during explosion of composite explosive.

Abstract:The polymer-bonded explosive(PBX) charge structures of certain ammunitions stored for 4, 8, 12, 16 years were investigated by CT scanning.The composition, density and precipitates of different storage periods were analyzed by gravimetric method, hydrostatic weighing method and IR.Simultaneously, the charge micro structures stored for 4, 12 and 16 years were observed by SEM.And the impact sensitivity was also investigated.Results indicate that PBX charge appears cracks, holes and cavities after long term storage.Meanwhile, the charge state is changed from sticky to solid along with silicon rubber separated out, and the rupture surface of charg changes from smooth to uneven.And also, the density, HMX content and impact sensitivity of charge storage for 4 years increase from 1.56 g·cm^-3 to 1.66 g·cm^-3 of charge storage for 16 years, 85% to 95% and 8% to 44%.The cracks may be caused by detachment of explosive particles from binder and microcracks propagation.And aging phenomenon of holes and cavities maybe appeared due to degradation of adhesive molecular network structure into small cyclic molecule.

Abstract:To understand the firing mechanism of underwater gun, a experimental platform was designed to simulate the interaction between cone-shaped multiple combustion gas jets and liquid.The influences from various injection pressures and nozzle diameters on multiple jets expansion characteristics was studied using a high-speed camera system.Experiment results show that increasing the injection pressure seems to improve expansion speed of jets and enhance flow turbulence and gas-liquid entrainment process.Injection pressure rises from 10.8 MPa to 28.8 MPa, expansion speed of central jet of nozzle A increases 28%, expansion speed of lateral jet increases 40%.The center orifice diameter increases from 2mm to 3mm, the maximum expansion speed of central jet and lateral jet increases 29%, 26%, respectively, and the speed decays faster as a another feature, while the lateral orifice diameter has little influence on expansion speed.

Abstract:To study the development and change characteristics of fuel-air explosive(FAE) cloud in the explosion dispersal process, the formation and movement state of clouds of FAE with different densities were observed by high-speed photography, the particle velocity changes of the central point on the outside surface of the fuel cylinder were calculated by numerical simulation and the changes of cloud relative concentration at 2.5 m from the explosive center were measured by photoelectric detection method.Results show that the fuel moves mainly in the form of jet prior to the formation of clouds, after what it moves mainly in the form of diffusion.The bigger the density of fuel, the bigger the cloud extended diameter at the same moment.Fuel particle velocity under the explosive dispersal condition experiences the process of first rapid increase and then slow decrease and the maximum value of the velocity is 377 m·s^-1. The change amplitude and frequency of fuel concentration show the change from big to small in the 10~80 ms, revealing that the fuel particle space distribution inside the throwing cloud has non-uniform distribution characteristics and the uniformity of fuel particle distribution can be improved effectively as the cloud movement time extends appropriately.

Abstract:To study the initiation/detonation characteristics of the shelled cast-cured polymer bonded explosive(PBX) caused by shaped charge jet, the impact test of the PBX explosive, overlaid by two groups of steel plates with thickness of 210, 255 mm and 165, 210 mm, was performed respectively by shaped charge with different forms and jet velocities, produced by the shaped charges with diameter of 82 mm, that is a small diameter and velocity is greater than 7000 m·s^-1 high-speed jet, another thicker diameter and about 5000 m·s^-1 jetting projectile charge.The shock initiation and detonation processes of the PBX explosive were observed and analyzed by high-speed photography.The experiment results were verified by LS-DYNA software.The values of initiation/detonation energy of the PBX explosive caused by different jets were obtained.Results show that jets formed by shaped charges with diameter of 82 mm can reliably cause the shock initiation and detonation of the PBX explosive overlaid by steel plates with thickness of less than 255 mm, can meet the needs of anti-missile warhead to damage the thick shell target.

Abstract:As the grain consolidation propellant charge was applied to traveling charge technique, a new traveling charge scheme was presented.The ignition delay time, mechanical strength, burning rate and stability of combustion performance for traveling charge were studied by the closed bomb and 30 mm ballistic gun test.The results show that the ignition delay time of traveling charge can be controlled by the time delay unit which relying on its high mechanical strength.The experiment results verify preliminarily that the combustion performance of traveling charge is basically stable.The increasing of the time delay unit thickness and ethyl cellulose(EC) content can make the ignition delay time of traveling charge prolong.The increasing of the binder content and pressed density can make the mechanical strength increase and combustion gas release rate decrease for traveling charge.The traveling charge has higher burning rate.When the binder content and the pressed density of traveling charge are 5% and 1.5 g·cm^-3, respectively, the maximum burning rate of traveling charge is 46 times as fast as 6/7 propellant.When the main charge dose and the time delay unit thickness are 113 g and 0.4 mm, respectively, the muzzle velocity in interior ballistic test increases by 73.3 m·s^-1 with an increase range of about 8%, compared with the standard projectile under the condition that the maximum chamber pressure does not change basically.

Abstract:In order to understand the reaction mechanism of TAT from DAPT, N-hydroxymethyl tertiary amines were prepared with secondary amines and formaldehyde as starting materials.The effect of ammonium nitrate on acetolysis reaction of N-hydroxymethyl tertiary amines was also studied.Results show that the acetolysis reaction occurres via N-attack instead of O-attack, then the N-hydroxymethyl is removed to obtain N-acylated product.Preparation of TAT was accomplished by hydrolysis and acetylation of 7-acetoxymethyl-1, 3, 5-triacetyl-1, 3, 5, 7-tetraazacyclooctane, which was converted from DAPT.The acetolysis reaction can be deactivated by nitrate, which is obtained from secondary amine and nitric acid, which is generated by acetolysis reaction of ammonium nitrate.The acetylation yield reduces 18%-41% in the presence of ammonium nitrate.

Abstract:To control the crystal form of hexanitrohexaazaisowurtzitane(CL-20) and reduce the mechanical sensitivity, nano-ε-CL-20/Estane particles were prepared by the suspension spray method with polyurethane elastic fibre(Estane) as coating agent.The particle morphology, particle size, crystal type, thermal stability and impact sensitivity of samples were characterized by scanning electron microscopy(SEM), laser particle size analyzer, transmission electron microscope(TEM), X-ray diffraction(XRD), and different scanning calorimetry(DSC) and mechanical sensitivity test.Results show that the Estane can be successfully coated on the CL-20 crystal surface and its particles are ellipsoidal or spherical with mean diameter of 456.3 nm.The CL-20 crystal form is still ε phase.The critical temperature of thermal explosion of raw CL-20, ε-CL-20/Estane made by aqueous suspension method and ε-CL-20/Estane made by suspension spray drying method is 224.57, 228.65 ℃ and 229.87 ℃, respectively.Compared to water slurry method, the impact sensitivity of ε-CL-20/Estane is reduced.The characteristic drop height is increased from 35.80 cm to 41.30 cm.

Abstract:Nine kinds of 7H-difurazano[3, 4-b:3′, 4′-f]furoxano[3″, 4″-d]azepine(a-i) were synthesized with 3, 4-bis(3-nitrofurazan-4-yl)furoxan(BNFF) as starting materials, and the SN2 mechanism of cyclization was discussed.The structure of these compounds were characterized by ¹H NMR, ¹³C NMR, IR and MS.Then 7-(2-amino-1-methyl)-difurazano[3, 4-b:3′, 4′-f]furoxano[3″, 4″-d]azepine(c) was used to synthesize two new compounds, N-(2′, 4′-dinitrophenyl)-and N-(3′-amino-2′, 4′, 6′-trinitrophenyl)-7-(2-amino-1-methyl) -difurazano[3, 4-b:3′, 4′-f]furoxano[3″, 4″-d]azepine(j, k), by reacting with 2, 4-dinitrochlorobenzene, 3-amino-2, 4, 6-trinitrochloro-benzene.The thermal properties j and k were analyzed by differential scanning calorimetry.Results show that the first and second exothermic peak of compound j are at 258.03 ℃ and 329.92 ℃, and for compound k, they are at 275.35 ℃ and 360.24 ℃, indicating that the introduction of nitrobenzene can increase the thermal stability.The detonation performances were estimated as follows:density, detonation velocity and detonation pressure of j and k are 1.68 g·cm^-3, 6945 m·s^-1, 21 GPa; 1.74 g·cm^-3, 6438 m·s^-1, 18 GPa, respectively.

Abstract:A new C—N bitriazoles compound 1-amino-3-nitro-5-(5-amino-3-nitro-1, 2, 4-triazole-1-yl)-1, 2, 4-triazole(DANBT) was synthesized with 5-amino-3-nitro-1, 2, 4-triazole(ANTA) and 1-amino-3, 5-dinitro-1, 2, 4-triazole(ADNT) as starting materials, and its structure and thermal performance were characterized by IR, MS, NMR and differential scanning calorimetry(DSC), respectively.Results show that the melting point and decomposition peak temperature are 221.8 ℃ and 291.8 ℃, indicating that NANBT has better thermal stability than ANTA and ADNT.The detonation velocity and detonation pressure calculated with the Kamlet-Jacobs equation of DANBT are 8.69 km·s^-1 and 33.91 GPa, respectively.

Abstract:2-Chloro-3, 5-dinitro-pyridin-4-amine was obtained by the nitration of 2-chloropyridin-4-amine as raw material, followed by condensation with 5-aminotetrazole, to give new 2-(5-amino-tetrazol-1-yl)-3, 5-dinitro-pyridin-4-ylamine(1) in yield of 64%.The new energetic compound 6-(5-amino-tetrazol-1-yl)-3, 5-dinitro-pyridin-2-ylamine(2) was synthesized by condensation of 6-chloro-3, 5-dinitro-pyridin-2-amine with 5-aminotetrazole in yield of 41%.The structures of compounds 1 and 2 were characterized by ¹H NMR, IR, MS and elemental analysis.Thermal behaviors of compounds 1 and 2 were studied by TG and DSC.The detonation velocity, detonation pressure and oxygen balance for compounds 1 and 2 were calculated.Results show that compounds 1 and 2 have same detonation velocity, detonation pressure and oxygen balance with the values of 8.18 km·s^-1, 30.7 GPa and -62.9%, respectively.The mass loss of compound 1 in the temperature range of 280-325 ℃ is 71%, while its decomposition temperature is 304.50 ℃.The mass loss of compound 2 in the temperature range of 285-415 ℃ is 65%, while its initial decomposition temperature is 310.67 ℃.

Abstract:Ultrafine CL-20/TNT cocrystal explosive was prepared by a spray drying method.Scanning electron microscopy(SEM) was used to characterize the particle size and morphology.X-ray diffraction(XRD) and differential scanning calorimetry(DSC) were utilized to determine whether the cocrystal explosive was prepared.Furthermore, the impact sensitivity of cocrystal explosive was tested.Results show that the prepared samples are not the mix of CL-20 and TNT but rather ultrafine CL-20/TNT cocrystal explosives.The particle size of cocrystal explosives are under 1 μm and they aggregate into many microparticles, which are spherical in shape and 1-10 μm in size.The melting point of ultrafine CL-20/TNT cocrystal explosive is 132.32 ℃.The thermal decomposition process can be divided into two stages.The peak temperatures of exothermic decomposition for first and second stage are 218.98 ℃ and 253.15 ℃, respectively.The characteristic height of CL-20/TNT cocrystal explosives is 49.3 cm, which increases by 36.2cm compared with raw CL-20.

Abstract:To simplify the preparation process of the nitrocellulose-based micro-pores spherical powder and make the internal pore structure more uniform, a new preparation process named as leaching method was studied.The dispeller way of solvent of late solvent distillation process was changed by replacing the heating distillation method with the leaching method of aqueous solution at room temperature and compared with solvent distillation method.The effect of two kinds of process parameters on the morphology, particle size, porosity and internal pore structure of the nitrocellulose-based micro-pores spherical powder was explored.The nitrocellulose-based micro-pores spherical powder was characterized by SEM and HopeImage software.Results show that the surface of nitrocellulose-based micro-pores spherical powder prepared by leaching method is smooth, its particles are mainly concentrated in about 20 μm, the spherical degree is 0.89, which is about 20% higher than solvent distillation method, the porosity is 92%, which is 10% higher than that of solvent distillation method.The distribution of the inner pore structure of the nitrocellulose-based micro-pores spherical powder prepared by leaching method is more uniform.

Abstract:In order to research the effect of combustion rate of the propellant on the operation process and the firing range of base bleed projectile, the flight ballistic of base bleed projectile was solved by using the computational aerodynamics coupled with particle trajectory.The changes of operation parameter, operation status, flow filed of base bleed projectile with time in the drag reduction stage were studied.The effect of combustion rate of propellant on the operation process and firing range of base bleed projectile were analyzed in detail.The simulation results are in good agreement with the target range test results of the standard base bleed projectile, indicating that the calculation model established is correct and reasonable.When the combustion rate adjustment coefficient changes from 0.8 to 1.2, the combustion time decreases from 36.4 s to 18.4 s, firing range decreases from 38.12 km to 36.21 km and the extended-range rate decreases from 33.32% to 26.64%.With the increasing of time, the base bleed parameters of the base bleed projectile with different combustion rate increase first and then decrease during the drag reduction period.The bleed mass flow rate of base bleed projectile with high combustion rate is larger than that of the base bleed projectile with low combustion rate, but there is no obvious increase of reduction drag effect.

Abstract:To regulate the thermal conduction performance of TATB-based polymer bonded explosive(PBX), the effects of graphite coating way(inner-coating and outer-coating), temperature and graphite content on the thermal conductivity of TATB-based PBX were investigated by a laser thermal conductivity apparatus.The thermal conduction mechanism of TATB-based PBX was analyzed by Agari model.Results show that the addition of graphite with high thermal conduction performance can improve the thermal conduction performances of TATB-based PBXs under room temperature, and the thermal conductivities of TATB-based PBXs with 1%(mass fraction) inner-coating and 1% outer-coating graphite are 0.572 W·(m·K)^-1and 0.697 W·(m·K)^-1, respectively, revealing that the outer-coating graphite way is better than inner-coating.Compared with the TATB-based PBX without graphite, thermal conductivities of TATB-based PBXs with 1% inner-coating graphite and 1% outer-coating graphite increase by 4.76% and 27.66%, respectively.With the increasing of temperature, the thermal conductivities of TATB-based PBX and its formulations modified with graphite gradually decrease.With increasing the graphite content, thermal conduction performances of TATB-based PBXs modified with outer-coating graphite increase.The 2%(mass fraction) outer-coating graphite can make the thermal conductivity of TATB-based PBX increase to 0.786 W·(m·K)^-1.The thermal conduction mechanism of TATB-based PBX and formulation modified with inner-coating graphite accords with the series model, whereas the thermal conduction mechanism of formulation modified with outer-coating graphite is between series model and parallel model.

Abstract:The rheological behavior, squeeze process temperature and the relationship between viscosity and temperature during the curing process of Glycidyl Azide Polymer(GAP)/hexanitrohexaazaisowurtzitane(CL-20) based composite explosives slurry were characterized by viscosity measurement technology.The impact of squeeze process temperature on the crystal form of CL-20 in composite explosives was characterized by X-ray diffractometer.Results show that the composite explosives slurry is a kind of pseudoplastic fluid and the optimal squeeze process temperature is 80 ℃.Moreover, the crystal form of CL-20 in the cured composite explosive is still ε-type.According to the rheological properties of the slurry, the dual Arrhenius viscosity model of the slurry is η_t=447.5329exp(25.20883/T)exp[0.02922exp(7.18748/T)t] at the condition of constant temperature.When the temperature are 20, 40, 60 ℃ and 80 ℃, the viscosity from this model is in good agreement with the experimental results.

Abstract:The explosive initiator used for aircraft is a product with high reliability and long life.In order to improve the storage life assessment precision of small sample size explosive initiator, through the analysis of the influence factors on storage life, an accelerated storage life model describing the relation of storage life and storage temperature for explosive initiator was established and a method suited for testing and evaluating the accelerated storage life of explosive initiator used for aircraft was proposed via a combination of sensitivity test and accelerated test.Based on the sensitivity test data of explosive initiator after acceleration and generalized linear model, the maximum likelihood estimations of the sensitivity distribution parameters were given.Then, the storage life assessment of explosive initiator used for aircraft was performed according to approximate normal characteristics of parameter estimations.The method was applied to one aircraft explosive initiator.The results show that the effective evaluation of explosive initiator required to store more than 15 years can be carried out via test data obtained by a sample size of about 150 and a period of about 40 days.

Abstract:Aluminum dust dispersion and flame propagation varying with time in 20 L cylindrical confined chamber were simulated based on computational fluid dynamics theory.The factors influencing flame velocity of aluminum dust were analyzed.Results indicate that when particle size of aluminum dust is in the range of 7-42 μm, the maximum explosion pressure(p_max) decreases with the increasing of particle size.The maximum of p_max and(dp/dt)_max are 0.876 MPa and 120.1 MPa·s^-1, and the minimum are 0.634 MPa and 19.5 MPa·s^-1, which are coincided with the experimental ones in literature with the deviations of p_max and(dp/dt)_max no more than 4.6% and 20%.When the ignition delay time is 60 ms, the flame propagation velocity along the radial direction falls first to a trough, then rises and falls at the end.The maximum and minimum of the velocity are 150.9 cm·s^-1 and 70 cm·s^-1, respectively.

Abstract:To identify whether hydroxylamine hydrochloride(HH) and N-methyl hydroxylamine hydrochloride(NMHH) are of autocatalysis characteristic, differential scanning calorimeter(DSC) and accelerating rate calorimeter(ARC) were used to test their thermal decomposition behaviors.Both dynamic and isothermal DSC results indicate an autocatalysis characteristic during their decompositions.And the heat of decomposition under 10 ℃·min^-1 were 2284.85 J·g^-1, 2188.41 J·g^-1 for HH and NMHH, respectively.ARC data show that the total decomposition time for HH and NMHH are both less than 30 min, and the maximum temperature rise rate are 193.4 ℃·min^-1, 218.9 ℃·min^-1, and the thermal decomposition very violent.Comparisons of ARC data of autocatalysis materials(HH, NMHH, trinitrotoluene(TNT) and so on) with that of non-autocatalysis materials(tert-butyl peroxy benzoate(TBPB), isooctyl nitrate(EHN) and di-tert-butyl peroxide(DTBP))show that the time difference from initial heat release to maximum temperature rise rate(t_0-max) for non-autocatalytic decomposition is much longer than that for autocatalytic decomposition, and the thermal inertia factor makes little influence on the law.So, the adiabatic test data t_0-max can be used to identify autocatalytic decomposition.

Abstract:The hydrocarbon oil and n-octanol were used to pretreat the waste solvents from 2, 4, 6, 8, 10, 12-hexanitro-2, 4, 6, 8, 10, 12-hexaazaisowurtzitane(CL-20) recrystallization process, and the white CL-20 solid was recovered.Ethyl acetate and chloroform were distilled by azeotropy for their different boiling points.The components of waste solvents and precipitated solid were characterized by high performance liquid chromatography(HPLC), fourier transform infrared spectroscopy(FTIR), scanning electron microscopy(SEM).Results show that the waste solvents mainly contain chloroform, ethyl acetate and α-CL-20.The purity of α-CL-20 recovered by hydrocarbon oil was 99.1% with the recovery rate up to 79.5%.

Abstract:Based on the two mechanisms of 3, 7-dinitro-1, 3, 5, 7-tetraazabicyclo[3,3,1] nonane (DPT) nitrolysis via HNO₃-NH₄NO₃ or HNO₃, the effects of NH₄⁺ in nitrolysis of DPT were studied by experiment and theoretical calculation. The effect of NH₄⁺ on the yield of HMX was studied with adding the ammonium salts including (NH₄)₂HPO₄, (NH₄)₂SO₄ and CH₃COONH₄ to nitrate solution system. Results show that the above-mentioned ammonium salts can improve the yield of HMX to 41.5%, 37.4% and 20.7%, respectively. Their function is similar to NH₄NO₃. In different nitric acid-ammonium salt systems, when the molar ratio of NH₄⁺ and DPT is close to 10, the yield of HMX reaches a maximum value of 56.3%, 52.2% and 35.5%, respectively. Results of the nitrolysis of DPT in nitric acid-ammonium salt systems and nitric acid-nitrate system are compared, finding that NH₄⁺ plays a dominant role in improving the yield of HMX. The reaction mechanism of NH₄⁺ in the nitrolysis process of DPT is theoretically explained by the density functional theory (DFT), deriving that the activation energy of DPT nitrolysis in HNO₃/NH₄⁺ is 133.95 kJ·mol^-1, lower than 376.73 kJ·mol^-1 in HNO₃.

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