Abstract:2,6,8,12-Tetranitro-2,4,6,8,10,12-hexaazaisowurtzitane (TNH₂IW) was synthesized from 2,6,8,12-tetraacetyl-2,4,6,8,10,12-hexaazaisowurtzitane (TAIW) by protection, nitration and deprotection. TNH2IW could also been obtained by reduction of hexanitrohexaazaisowurtzitane (HNIW, CL-20) with SnCl₂. The molecular geometries, electric structures, and thermodynamic properties of TNH₂IW were calculated using the density functional theory (DFT) method at the B3LYP/6-31G* level. The thermodynamic parameters including heat capacities and entropies were calculated, and also the polynomial functions between thermodynamic parameters and temperature were determined. The accurate heat of formation 461 kJ·mol^-1 of TNH₂IW in gas phase was obtained via designed isodesmic reaction in which the cage and the nitro group have been kept. The data obtained from the present study show a satisfactory detonation performance, with detonation velocity of 9.13 km·s^-1 and detonation pressure of 38.9 GPa, both of which are higher than those of TNT and RDX, not worse than those of HMX counterparts.

Abstract:Abstract：Via the molecular structure analysis of aromatic polynitro compounds, bonds in the molecules were coded by bond parameter method and fitted with mathematics method. The obtained regression model was tested and corresponded to the statistics rules. The results of multiple linear regression show a good correlation between the enthalpy of formation and the bond parameters. Correlation coefficient R=0.994, determination coefficient R²=0.988. And the relative error between the predicted values and literature ones of the enthalpy of aromatic polynitro compounds is mostly within ±10%.

Abstract:To find suitable components for energetic eutectic mixtures, 3-amino-2,4,6-trinitroanisole with an overall yield of 76% was synthesized via the sequence methylation-VNS amination of commercial picric acid. And its properties were preliminarily studied by IR, 1H NMR and elemental analysis. The mechanism of methylation and VNS amination were discussed. DSC-TG curves show that the endothermic peak temperature is 133.77 ℃ and the exothermic peak temperature is 254.10 ℃. The massloss is about 1.71% at 199.6 ℃. H₅₀ is 82.5 cm and the friction sensitivity is 0%. V₅₀ is 11.42 kV and E₅₀ is 1.99 J. The theoretical detonation velocity is 7.459 km·s-1 (ρ=1.709 g·cm ^{-3), and the theoretical detonation pressure is 22.9 GPa (ρ=1.709 g·cm -3). Results show that 3-amino-2,4,6-trinitroanisole is stable to heat. The theoretical detonation velocity and pressure of 3-amino-2,4,6-trinitroanisole are larger than that of TNT.}

Abstract:Taking N-tert-butyl-3,3-dinitroazetidinium nitrate (BDNAN) as precursor,1,3,3-trinitroazetidine(TNAZ) was synthesized by five different nitrolysis systems. The optimal nitrolysis system was NH₄NO₃/Ac₂O. At the same time,the reaction conditions were optimized, and the optimal reaction conditions are as follows: n(Ac₂O):n(BDNAN)=25:1, reaction temperature is 80 ℃ and yield is 83.1%. The thermal characteristics and the split mechanism of TNAZ were studied. Results show that TNAZ having a stable four-membered ring skeleton melts at 99.5 ℃ with decomposition at 264.68 ℃.

Abstract:The recrystallization of ammonium perchlorate (AP) was carried out using supercritical CO₂ as the anti-solvent and ethanol as solvent. The volumetric expansion curves of CO₂-ethanol were measured and the vapor-liquid equilibrium of CO₂-ethanol system was calculated with Peng-Robinson equation. The effects of the main operation parameters on the result of the gas anti-solvent(GAS) recrystallization process were studied experimentally, such as the initial concentration of the solution,the final pressure and hold time after the pressurization. It is shown that the average grain size increases when the temperature rises. And the average grain size decreases when the initial concentration increases at 25 ℃ and by contraries at 31 ℃ and 40 ℃. Meanwhile the faster the pressure raising,the more uniform little AP grain could be produced. If the final pressure is more than 9 MPa, the increase of pressure has little effect on average size of AP particle. When the pressure is 6 MPa, the increase of hold time leads to a significant increase of the average grain size with a wide distribution. But when the final pressure is 9 MPa, there is a little change in size, only a slight change in its morphology. The effect of the intensity of liquid flow and the physical and chemical properties of the solvent itself were prevailing when compared to the effects of the other operation parameters. Finally, AP particles (60 nm, polyhedron) with narrow size distribution were obtained at 9 MPa, 25 ℃ and 35 kg·h^-1, and the phenomenon of intercrystalline fracture was found in AP particle.

Abstract:In order to compare and analyze the shock wave sensitivity of a new aluminum explosive, the initiation behavior of two aluminum explosives (HL-10-L-1 and HL-109-L-1) under long period and low value impulse loading were studied using big gap test and numerical calculation. The critical gap thickness and ∫p²dt of nondetonation and nonviolence reaction were obtained. Analysis shows that adopting ∫p²dt value to infer the reaction behavior of explosive under low value pressure pulse is more reasonable than the critical gap thickness.

Abstract:The crystal internal defects of RDX/HMX were studied by optical microscopy with matching refractive(OMS), small angle scattering of X-ray(SASX),atomic force microscope(AFM), sink-fload method(SFM) and Mirco-CT. OMS and AFM results show that RDX/HMX has more defects and cracks than reduced sensitivity-RDX/reduced sensitivity-HMX. SASX results show that crystal internal defects of RDX/HMX are larger than that of RS-RDX/RS-HMX, and mirco-CT results show that RDX has larger internal defects than RS-RDX. Furthermore, shock sensitivity of RDX based PBXs and RS-RDX based PBXs were studied, and the results show that internal defects of RDX has great influence on shock sensitivity of RDX.

Abstract:The accelerated thermal aging tests of PBX based on TATB were carried out by using a hot air oven from 55 ℃ to 75 ℃. The mechanical properties such as tensile strength, elongation at failure and modulus were measured before and after aging. Morphology of rapture section from tensile test at 55 ℃ was observed by using scanning electric microscopy (SEM). Results show that the mechanical properties and the interfacial mechanism between binder and TATB crystal do not undergo changes significant during the aging period.

Abstract:Ignition temperature of 2Al/Fe₂O₃ thermite was studied by analysis and experiments. Failure temperature of aluminum particle oxide film was analyzed according to the weight,resistance and appearance of aluminum powder undergoing different temperatures. Critical ignition temperatures of thermite spheres with different radii were calculated by Frank-Kamenetskii theory and measured by a high-temperature muffle furnace. Results show that the protective film fails almost completely at the melting point of aluminum,and ignition occurs at temperature of about 1600 K, and the independent of the volume of thermite sphere and ignition temperature is not correctly calculated by the Frank-Kamenetskii theory of homogeneous combustible system.

Abstract:Glycidyl azido polymer (GAP) was modified with hydroxy terminated polybutadiene (HTPB) to improve the mechanical properties of GAP. Effects of different reaction conditions on mechanical properties of blend binders were discussed. Static tensile test results show synergy effect on mechanical properties of blend binders, and tensile strength and maximum elongation could reach 3.833 MPa and 593% while weight ratio of GAP and HTPB is 1:1. Tanδ-T curve from dynamic thermomechanical analysis shows single glass transition temperature near -60.2 ℃, implying that reactive compatibilization of immiscible GAP/HTPB blend binders could be got by controlling the curing reaction conditions. Micromorphology of GAP/HTPB blend binders displayed in SEM photos formed corroborating with the former two conclusions. In a word, HTPB/GAP blend binders with excellent mechanical properties possessed a good prospect for applications of GAP in composite solid propellents.

Abstract:The effects of 3,4-dinitrofurzanfuroxan (DNTF) contents on dynamic mechanical properties of modified double-base propellants (DNTF-CMDB, DF) were studied by dynamic mechanical analyzer (DMA). The characteristic values of dynamic mechanical properties at multi-frequency for DF propellants were obtained. Results show that two β-relaxations, besides a α-relaxation, appear on DMA curves of DF propellants, and β₁-relaxation is due to the effect of DNTF. It is shown that the DNTF content can obviously affect the dynamic mechanical properties of DF propellants. The correlations between the tanδ peak temperature T_α in the α -relaxation, the free volume expansion coefficients α_f of α -relaxation and β-relaxation and the sum of ratios NG/NC and DNTF/NC were obtained. The DF propellants with 20% DNTF have optimal mechanical properties at high and low temperatures.

Abstract:The effect of magnesium powder particle size on the combustion properties of Mg/PTFE fuel-rich propellant was studied. The thermal properties of Mg/PTFE were studied by using differential thermal analysis(DTA) and thermogravimetry(TG). The linear and molar burning rate were measured by high speed photography, and the flame temperature was surveyed by infrared radiation thermometers. The results show that reducing magnesium powder′s size had little weight on thermal analysis but steps up burning velocity even more than three times. The flame temperature of pyrotechnic fuel rich propellant heighten about 170 ℃ along with the diameter of magnesium powder decrease.

Abstract:Three cutting machines were selected to study the comminution of HTPB, including cage wet grinder,dry cyclone and long-range control cutting machine. Using diameter ratio and loss rate of AP and Al as standards, dry cyclone is comparatively smashed method at present. The diameter of smached materials was about 1 mm, 8^# detonator could be ignited by the commercial explosive prepared with the materials.

Abstract:In order to predict the service life of propellant exactly, data change of mechanical properties was used to estimate ageing failure of propellant. Adopting the method of heat-accelerated ageing test, the relationship between the mechanical properties including impact strength, compression strength and compressibility and ageing time and temperature were studied. Results show that the decline of mechanical properties of polymer materials caused by ageing, decay will not influence the safety service of RB nitramine propellant, and the service life of RB nitramine propellant exceeds its safety storage life obviously.

Abstract:An experimental device that additional chambers were mounted on a barrel of 14.5 mm ballistic machine gun was adopted in order to study the pressure platform-like effect of increasing muzzle velocity with a barrel additional charge. The 6/7-XDGZB gun propellant was used as the main charge, and the 4/1-XDZJ was used as the additional charge. The results of closed bomb experiment and interior ballistic experiment show that the 6/7-XDGZB gun propellant has the characteristics of lower initial burning rate, and the 4/1-XDZJ gun perpellant with higher burning rate has property of regressive burning. The two charges burn in coordination in their respective chambers, and the muzzle velocity of the additional charge can rise from 981 m·s^-1 to 1063 m·s^-1 compared to the blank charge (i.e. main charge only, no additional charge) under the condition in keeping the maximum pressure unchanged, and piezometric efficiency can rise from 0.47 to 0.58.

Abstract:A suit of on-line test equipment based on electrochemical sensor was used to determine detonation gaseous products of a thermo-baric warhead. The arrangement and protection of the equipment was investigated, and the concentration-time curves of gaseous products in thermo-baric warhead detonation were obtained. The anoxia asphyxia effect and the miasma asphyxia effect were proposed and calculated. Detonation gases determination results of three kinds of charges show that the anoxia asphyxia and miasma asphyxia effects of thermo-baric warhead are stronger than that of normal charge, and the anoxia asphyxia effect is more obvious than CO miasma asphyxia effect.

Abstract:The relationship between loading pressure and charge density is the fundamental parameters for micro-charges. It is very important to study and design the charge density,loading explosive weight,and detonation characteristics in micro-electro-mechanical systems (MEMS) fuzes. The relationships between loading pressure and loading density by volumetric method for two primer explosive lead azide carboxymethyl cellulose (CMC-Pb(N₃)₂) charges (micro-charge with internal diameter 0.9 mm and normal charge with internal diameter 5.28 mm) were studied. The fitting equations and relationship curves for the two charges were obtained,and the relationships between porosity and stress were got too.

Abstract:Mg/PTFE thin film pyrotechnic was produced by magnetron sputtering and evaporated deposition using magnesium as the combustible and polytetrafluoroethylene as the oxidant. The differences of the two film technologies were investigated and the adhesion,the granularity and the burning rate of the thin film were measured. Results show that the adhesion,the granularity and the burning rate of the Mg/PTFE film produced by magnetron sputtering are 35.88 mN, 0.1-0.5 μm and (623.9±12.5) mm·s^-1 respectively,and the main performances of the Mg/PTFE film produced by magnetron sputtering are better than that by evaporated deposition.

Abstract:The change of an initiating device′s function time was studied by accelerated life test at 60 ℃, and relative humidity 95%. Results show that the mean value of the detonator′s single function time prolongs when the time of life test continues. And at the ageing time of 0, 21, 35 and 45 days, the maximum value of function time and the ageing time have good linear relatiouship. The reliability value of the tested sample falls to 98.98% when the ageing time is 56 days, and falls to 15.06% when the ageing time is 67 days.

Abstract:A new powerful primary explosive nickel hydrazine azide(NHA) was used as charge for semiconductor bridge(SCB). The optimal conditions for the ignition were obtained: pressure 60 MPa; capacitance 47 μF; particle size of the primary explosive 49 μm. U-t curves and U-E curves show that NHA is ignited by the plasma generated by SCB at high voltage,and NHA is ignited by hot spot generated by SCB Joule-heat at lower voltage.

Abstract:A one-dimensional unsteady flow calculation model of a base bleed unit interior ballistics was established based on the theory of homogeneous flow and solid rocket engine. The inner flow field of base bleed unit and exterior trajectory of a base bleed projectile were simulated via calculating interior and exterior equations of base bleed projectile. The distributions of pressure, temperature, density and velocity of gas and their changing laws at nozzle were investigated and obtained. The calculational results show that the highest temperature and velocity of the gas are 1944 K and 65 m·s^-1. The working time of base bleed unit is 24 s and increasing range rate is about 30%. Both of working time and increasing range rate are in good agreement with the results obtained from practical shooting tests.

Abstract:A new powdery ammonium nitrate fuel oil explosive was produced to solve the problems of complicated production process and low explosion energy. The explosive was made of ozocerite,surfactant,gelatinizer and water, which were made into slurry mixed solution at 105-110 ℃, and was dehydrated from -0.07 MPa to -0.09 MPa. The microstructure and sensitivity of the explosive were analyzed,and the effects of the charge density on detonation velocity and underwater explosion energy were also studied. Results show that the mixing uniformity of the components and safety are good. When the charge density is 0.91-0.94 g·cm^-3,the detonation velocity is more than 4000 m·s^-1, and the underwater explosion energy is more than 3700 kJ·kg^-1,which is close to the theoretical calculation value.

Abstract:A high performance liquid chromatography (HPLC) method was developed for the separation of 1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane (TAT) and 1,3,5-triacetyl-1,3,5-triazacyclohexane (TRAT), which are the intermediates for the synthetic reaction of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX). The chromatograms of TAT and TRAT were further confirmed by high performance liquid chromatography-mass spectrometry (HPLC-MS). The optimal separation conditions are: sillca column (4.6 mm×250 mm i.d., 5 μm), mobile phase: acetonitrile/water (75/25, V/V); the flow rate is 1.0 mL·min^-1, the wavelength is 215 nm, the injection volume is 20 μL.

Abstract:The studies and developments in science community of energetic materials with damage mechanics were introduced from two aspects, which are the macro-mechanics phenomenon and the micro-statistic mechanics. The description viewpoints and application ranges of each model were compared and analyzed. It′s necessary to upbuild the multi-scale analysis model, and systematically investigate the damage evolution under different loading modes to establish more reasonable constitutive model of energetic materials.

Abstract:The ageing research of insensitive RDX (I-RDX) and polymer bonded explosive (PBX) were reviewed. The crystal characteristics of RDX and evaluation methods, and the crystal characteristics and impact sensitivities of I-RDX and I-RDX based PBX before and after aging were summarized. The impact sensitivities of I-RDX crystal without cyclotetramethylene tetranitramine (HMX) or with a little HMX, or with blending some HMX, have no evident change. Influence mechanism of HMX in I-RDX crystal was discussed.

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