Abstract:Bruckman-Guillet′s formula for calculating the critical temperature of hot-spot initiation(T_cr) in energetic materials(EMs) was derived. A numerical method of estimating the value of T_cr was presented. The corresponding computer program was programmed. The literature values of T_cr of nine EMs: PETN,RDX,HMX,EDNA,tetryl,EDADN,AN,NG and TNT,were certificated with the programmed program,considering that the programmed program is suitable for fast computation of T_cr and reported values of T_cr for eleven EMs: TATB,HNS,HNDACO,HHTDD,BTNDNG,keto-RDX,BTNEDA,PBX-JH-94,PBX-JO-96,TB propellant M32 and TB propellant SD are believable to a certain extent.

Abstract:The enthalpies of formation for energetic thermoplastic polyurethane elastomers(ETPE) based on glycidyl azide polymer(GAP), poly glycidyl nitrate(PGN), poly bis-azidomethyl oxetane(PBAMO), poly(3-nitratomethyl-3-methyloxetane)(PNIMMO), bis-azidomethyl oxetane-azidomethyl methyl oxetane (BAMO/AMMO) copolymer as soft segments,diphenylmethane diisocyanate(MDI), toluene diisocyanate(TDI),isophorone diisocyanate(IPDI) as hard segments and butadiene(BDO) as chain extender were estimated by group additivity method. The results show that the enthalpies are affected by the different soft segment type,hard segement type and the hard segment contents. The enthalpies of formation of the ETPE reduce with the increasing of the hard segments contents. The enthalpy of formation of MDI based ETPE is higher than that of the other isocynates. The enthalpies of formation of azide polymers based ETPEs are higher than that of nitrate ester polymers. The estimated enthalpies data of ETPEs can help to design high energy propellants.

Abstract:To evaluate the effect of the tapered round pipe geometry,volumetric flow rate and gellant type or content on the pressure drop,the velocity and viscosity fields,the governing equations of the steady,incompressible,isothermal,laminar flow of a Power-Law,shear-thinning gel propellants in pipe were formulated,discretized and solved. A SIMPLEC numerical algorithm was applied for the solution of the flow field. Results show that the mean apparent viscosity decreases with increasing of the volumetric flow rate and increasing of the gellant content results in an increase in the viscosity. The results also show that the cone semi-angle can produce additional decrease in the mean apparent viscosity of the fluid. The mean apparent viscosity decreases significantly with increasing of the convergence angle of the pipe,and its value is limited by the Newtonian viscosity η_∞. The effect of the cone semi-angle on the mean apparent viscosity is more significant than that of the volumetric flow rate and the gellant type or content on the mean apparent viscosity. Additional decreasing of the viscosity results in an increase in the pressure drop with the increasing of cone semi-angle. It is important to pipe design that the viscosity decreasing and the pressure drop increasing are taken into account together.

Abstract:To increase fragment warhead performance,aimable fragment warheads were widely designed and developed to obtain high lethality against air target. A certain focusing fragment warhead driven by two different places of detonation respectively,were numerically simulated by using DYNA3D. To obtain the fragment distribution density,target was modeled numerically at 6 m far away from the fragment warhead. The simulation results show that the fragments can focus on the target,and the fragment ejection angle and azimuth angle agree with each other. The velocity of directional fragment under two asymmetric points initiation is 20.3% faster than that under the center initiation,and the fragment distribution density under two asymmetric points initiation is 9.6% greater than that under the center initiation. Simulation results could be used for the initiation system of focusing fragment warhead in engineering practice.

Abstract:Energy output models for the ideal explosives and aluminized explosives were introduced. These models were used to calculate far-field UNDEX of TNT and PBXW-115 with AUTODYN software. Performance parameters such as peak pressure, time constant, impulse, energy flux density and shock wave energy were calculated. These parameters were compared with experimental data. The dynamic model of high pressure gas bubble in uncompressible liquid was achieved. The dynamic equations and JWL EOS (Equations of State) of the detonation products were both used to calculate bubble parameters. Bubble periods of 1 kg TNT and PBXW-115 are 0.213 s and 0.283 s. Bubble energy are 1.88 MJ·kg^-1 and 4.41 MJ·kg^-1, respectively. Bubble parameters calculated are consistent with experimental data.

Abstract:In order to study the characteristics and the influence factors of the parameter estimation of Neyer D-optimal sensitivity test,the effects of the initial guesses of parameters and the sample size on the precision of parameter estimation were studied by computer simulation. Results show that the mean estimation is unbiased; about one-third of the standard deviation estimation is smaller and two-thirds of the standard deviation estimation is bigger; the initial guesses of the parameters have a little effect on the precision of parametric estimation; a better mean estimation can be obtained if sample size is more than 18.

Abstract:Three high-density hydrocarbons with molecular structure of C₁₀H₁₆ (C10), C₁₅H₂₂ (C15) and C₂₀H₂₈ (C20) were synthesized using dicyclopentadiene as feedstocks. The density of the fuels increases in the order of C10,C15 and C20,whereas the low-temperature properties show the inverse tendency. To obtain higher density and acceptable low-temperature property,binary and ternary blendings of them were prepared. The dependence of density and viscosity on the composition of blends was analyzed,and an equation was established to predict the density of blendings. C10 can improve the low-temperature of blendings,whereas C20 can enhance the density. According to the density-viscosity-composition ternary diagrams,an optimized blending composition of C15≥75wt%,C20≤20wt% and C20≤5wt% was determined. The resulting fuel has density larger than 1.0 g·cm^-3 (15 ℃),volume heat larger than 42.0 MJ·L^-1,viscosity smaller than 500 mm²·s^-1 (-40 ℃),and pour point smaller than -70 ℃, which is very promising for propulsion applications.

Abstract:In order to study the reaction mechanism of nitration/nitrolysis of tetraacetylhexaazaisowurtzitane(TAIW) with the mixture of nitric acid and sulfuric acid,all of the intermediates,tetraacetyldinitrohexaazaisowurtzitane,triacetyltrinitrohexaazaisowurtzitane,two isomers of diacetyltetranitrohexaazaisowurtzitane and monoacetylpentanitrohexaazaisowurtzitane were separated by means of quenching the reaction mixture at proper time and characterized by element analysis,NMR,FTIR,MS and X-ray diffraction. The results show that the two free secondary amines of TAIW are nitrated firstly and then the four acetyl groups of TAIW are nitrolysed one after one under conditions of elevating the reaction temperature. Moreover,all of the intermediates stated above of the nitration processeses were detected by thin layer chromatography(TLC) techniques.

Abstract:2,6-Diamino-3,5-dinitropyridine-1-oxide (ANPyO) was synthesized with 2,6-diaminopyridine as a starting material by acetylation, N-oxidation, nitration and hydrolysis steps in turn, and the yield of ANPyO was up to 81%. The main factors affecting the acetylation, N-oxidation and nitration were investigated, and the structures of intermediates and ANPyO were characterized by ¹H NMR,MS and IR spectra.

Abstract:5-Hydrazinotetrazole as an intermediate was synthesized from 5,5′-azotetrazolate by acidizing of hydrochloric acid and recrystallizing of sodium acetate,respectively. 5-Hydrazinotetrazole mercury perchlorate (HTMP) was synthesized from 5-hydrazinotetrazole by complex reaction with mercury acetate and perchlorate. Its structure was characterized by using Fourier transform infrared (FTIR), energy dispersive spectrum (EDS) and elemental analysis. Thermal decomposition of HTMP was discussed. The laser sensitivity of HTMP was tested by Langlie method. Results show that HTMP is sensitive to laser. Under no-doping condition, the 50% ignition energy of HTMP is 972 mJ, while BNCP could not be ignited. When doping 5% carbon black by weight, the 50% ignition energy of HTMP and BNCP are 2.56 mJ and 59 mJ. Mechanical sensitivity of HTMP is similar to that of BNCP.

Abstract:The crystallization characteristics of casting molding of TNT explosive was on-line studied by high-resolution X-ray computed tomography and the three-dimensional structure information and distribution rule were obtained. The results show that the rate of solidification is the highest at starting and slows down. TNT crystal is fine at first and subsequently columned and branch crystal is formed before solidification. The TNT branch crystal has obvious tropism characteristics. The shrink hole is mainly concentrated hole and small hole. The shrink holes intersect and become bigger during solidification and stable at last. They are much smaller at side and bottom and accordingly the density is higher. The volume shrink ratio is over 20% after solidification. The linear density difference between the bottom and the middle is about 1.5%-8% but up to 5%-18% between the surface and the center.

Abstract:The coaxial measurement of electrical conductivity was improved by using shock initiation method,and the conductivity formula was derived. The suitable shock wave pressure was input to limit the shock wave reverberation in reaction zone and instability in detonation growth. And the conductivity curves of cast TNT and TNT/RDX compositions were studied. The chemical reaction times and the reaction zone widths were acquired by analyzing the inflexions in curves. Results show that the maximal conductivity decreases with the increasing of RDX in cast TNT/RDX compositions. The reaction time of cast TNT is about 0.08 μs, and the reaction zone widths of cast TNT and several TNT/RDX compositions are about 0.4 mm and 0.5 mm respectively.

Abstract:The thermal safety of 2,4-dinitroanisole(DNAN) explosive was studied by cook-off test. The self-ignition temperature,the delay time of thermal explosion and the critical temperature for the thermal explosion of DNAN were obtained,and the test results were compared with that of TNT. The results show that the self-ignition temperature of DNAN is 346.7 ℃,the temperature of 5 s explosion point is 374.1 ℃, and activation energy is 48.37 kJ·mol^-1. Under the ambient temperature of 220 ℃,when DNAN is placed for 48 h, DNAN is nonflammable. DNAN is semi-burned under the ambient temperature of 230 ℃. When the temperature reaches above 240 ℃, thermal decomposition reaction of DNAN occurs. The delay time of thermal explosion was obtained from theoretical calculation at 100 ℃. Results show that DNAN is stable and safe in the melting process of temperature below 100 ℃.

Abstract:Solvent/nonsolvent recrystallization method was used to prepare HNS/HMX mischcrystals in order to increase the energy output of HNS-Ⅳ,and its structure characterization and performance were studied in detail. Results show that β-HMX is surrounded by superfined HNS particles in the core. The specific surface area,impact sensitivity,friction sensitivity,and initiaiton energy of HNS-Ⅳ,superfined HNS/HMX(80/20) and superfined HNS/HMX(70/30) are as follows: 14.25 m²·g^-1,9.98 m²·g^-1,9.56 m²·g^-1； 52%,76%,78%; 14%,16%,19%; 0.49 J,0.50 J,0.58 J respectively.

Abstract:Submicron/nano-HNS with different morphologies was prepared by prefilming twin-fluid nozzle assisted solvent and non-solvent crystallization process. By controlling of non-solvent temperature,non-solvent pH value and different surfactants,the effect of these factors on morphology of submicron/nano-HNS were analyzed. Results show that the morphology of HNS changes from short plane-like shape to long plane-like shape when non-solvent temperature changes from 25 ℃ to 50 ℃. The morphology comes through the variety of ellipsoid,short plane-like and club-shaped with pH value of non-solvent from acidity to neutral and finally basical,with the particle size distribution in 50-300 nm,50-500 nm,and 50-600 nm,respectively. Ellipse plane-like and long club-shaped morphology HNS were obtained using white dextrine and sodium carboxymethyl cellulose (CMC-Na) as surfactants in non-solvent,with the particle size distribution in 50-300 nm and 50-600 nm.

Abstract:The recrystallization process of RDX from concentrated nitric acid was studied to prepare the spherical RDX with particle size of 150-180 μm. The manufacturing process conditions are: RDX 35 kg,concentrated nitric acid (97) 135 kg,stirring rate 240 r·min^-1,the first diluent: dilute nitric acid (50%) dosage 80 kg,adding rate 8 kg·min^-1,temperature 45 ℃,heat preservation 10 min； the second diluent: water dosage 126 kg,adding rate14 kg·min-1,temperature 55 ℃. Results show that the content of particle size of RDX crystals from 150 μm to 180 μm are 69.3% by using the recrystallization process mentioned above.

Abstract:The standard molar enthalpies of series of energetic coordination compounds solution with carbohydrazide as ligand and nitrate or perchlorate as anion in deionized water were measured by a Setaram C80II microcalorimeter at 298.15 K. Based on these values, their lattice energy were calculated through Kapustinkii formula, meanwhile the thermochemistry radius of ［M(CHZ) ₃］²⁺ (M=Mn, Zn, Ni) was gained. The relationship between lattice energy and impact sensitivity or friction sensitivity was discussed. Results show that the lattice energy of perchlorate are smaller than their corresponding nitrate, thus the perchlorate are more sensitive.

Abstract:The effects of ammonium nitrate on energy of gun propellant were studied. The explosion heat at constant volume, isochoric adiabatic flame temperature, specific energy, covolume and specific volume of propellant gas were calculated by the minimum free energy method. The specific energy and covolume were tested by closed-bomb method. The explosion heat was tested by heat insulation method. The calculated results show that when the contents of ammonium nitrate are 58.49%,50.07% and 43.13%,the explosion heat,the flame temperature and the specific energy of gun propellant are 4743.2 kJ·kg^-1,3075.9 K and 1049.6 kJ·kg^-1, respectively. The testing results show that when the contents of ammonium nitrate are 50.0% and 40.0%, the explosion heat and the specific energy of gun propellant are increased by 23.6% and 5.0% respectively comparing with that of single-base propellant. With the increasing of content of ammonium nitrate, changes of explosion heat and specific energy are consistent with the calculated results.

Abstract:In order to study the effects of phases of HMX on the nitramine propellants,the combustion performance and mechanical properties of nitramine propellants containing α-HMX and β-HMX were tested by closed combustion bomb and mechanical properties tester. Results show that the propellant with α-HMX is easy to be ignited and its gas generation brisance and combustion rate is lower than that with β-HMX,and the burning rate pressure exponent of the propellant with α-HMX is 0.1 higher than that with β-HMX and mechanical properties of the propellant with α-HMX is worse. In addition,when loading density is 0.12 g·cm^-3, the two burning rate pressure exponents are larger than 1,and when loading density is 0.20 g·cm^-3, the two burning rate pressure exponents reach the level of less than 1.

Abstract:The ANFO (ammonium nitrate and fuel oil) were modified by six kinds of surfactants including SDBS (sodium dodecyl benzene sulfonate),special expanded reagent, CTAB (hexadecyl trimethyl ammonium briomide),KH560 (γ-glycidoxypropyl trimethoxysilane), Tween80 (polyoxyethylent (80) sorbitan monooleate) and TX-10 (polyoxyethylene octylphenol ether). The SEM technique and the plate trace principle test method were used to study their particles microstructure and detonator initiation sensitivity. Results show that the effects of the surfactants are evident on both particles microstructure and detonator initiation sensitivity of ANFO. The modified ANFO with SDBS can not be initiated under detonator shock wave action,since its particle shows a sandwich shape with smooth particle surface and fewer pores. While other modified ANFO can be initiated due to their coarse particles surface and porosity.

Abstract:To explore the storage properties of the emulsion explosive after pressed by shockwave,the explosion shock wave of the emulsion explosive was tested at a period after it was pressed by shockwave in water,and the storage properties were compared and judged with its explosion shockwave crest values. The results show that there is no obvious decline of the explosion shockwave crest values in a certain period after pressed by the outside shockwave,but the explosive capacity will be worsen quickly after this period and lose the priming sensitivity by cap. The period of keeping the cap sensitivity may be several minutes,some days or even several weeks,which is related to the intensity of the pressing shockwave,the emulsifying agent,the sensitizer etc. The relationship is that the period will be shorter with the increasing of the shockwave intensity,and it will increase with the increasing of emulsifying agent content,and when the emulsion explosive is pressed by the shockwave with 108 MPa peak pressure,the period of keeping cap sensitivity declines from over 18 h to less 1 h with the increasing in the mass percent of the hollow glass microballoon from 2% to 5%,and with the increasing of the mass percent of the expanded perlite from 2% to 5%,the period declines from 24 min to several minutes.

Abstract:To study the effect of HNS-Ⅳ charge parameters on the performance of exploding foil initiator (EFI),the function time of EFI with different charge parameters was measured. Results show that EFI with charge density of 90% theoretical maximum density (TMD) has the shortest function time and maximum initiation sensitivity. The initiation sensitivity of EFI with charge densities of 60% and 98%TMD is very low. When the charge density is 90%TMD,charge diameter has little effect on the initiation sensitivity and function time of EFI.

Abstract:In order to find the effect of the ignition composition amount on the short impulsive thruster and select the right ignition composition amount,the simulated test device was used and the p-t curves were obtained. Results show that the ignition delayed time changes from 1.48 ms to 1.06 ms,and the pressure increasing time changes from 0.37 ms to 0.16 ms,and the action time is about 1 ms. It indicates that the ignition delayed time and the pressure increasing time can be shortened if the ignition composition amount is increased. The ignition composition amount of 80 mg is selected to meet the target requirements.

Abstract:By calculating the output synchronous error of the main parts of the flexible explosive circuit,the main factors affecting the output synchronization were analyzed. Two kinds of explosive circuit (one in nine out eccentricity explosive circuit and one in twelve out center explosive circuit) samples based on silver code were produced. The charge of the column and the code were HMX CⅢ. The output performances of these explosive circuit samples were tested. The results show that the function of the explosive circuits can be accomplished. The synchronous error of the circuit is within 200 ns which is better than that of the similar circuit.

Abstract:The effects of dopant variety,dopant content and dopant wavelength on tetraamnine bis(5-nitrotetrazolato) cobalt(Ⅲ) perchlorate(BNCP) semiconductor laser sensitivity were studied by doping different dyestuffs into BNCP. Results show that the laser ignition threshold value is reduced apparently by adding appropriate dopant variety and dopant content. In 635 nm wavelength,the ignition energy of BNCP doped with 5% copper phthalocyanine is the lowest,and the laser 50% initiation threshold value and the initiation explosive average delay time of BNCP are 0.24 mJ and 2.3 ms. And for BNCP doped with 5% carbon black, the laser 50% initiation threshold value and the initiation explosive average delay time of BNCP are 0.57 mJ and 5.5 ms. In 915 nm wavelength,the 50% ignition threshold value of BNCP doped with 5% carbon black is the lowest (5.06 mJ).

Abstract:To study the application of Al/Ni multilayer films in micro/nano ignition apparatus,the propagating velocity of reaction waves in multilayer films was calculated by extended Mann model. The Mann mathematical model was extended by defining the layer thickness ratio to be δ：(2b-1) δ so as to account for multilayer films that have alternating layers with different layer thickness. The propagating velocity of reaction waves in Al/Ni multilayer films was computed and the calculation results agree with the experimental results,which verified the extended model. Results show that there is a critical layer thickness,below which the propagating velocity increases with the increasing of bilayer thickness; while above the critical value,a reverse relation is observed.

Abstract:Humidity aging experiments of investigating effects of environmental humidity on NEPE propellant were carried out. Mechanical properties, humidity absorption ratio, and variation of stabilizers content of NEPE propellant were measured. Results show that absorption humidity seriously affects mechanical properties of the NEPE propellant. Tensile strength may decrease by 70% of initial value in 85% RH condition. The NEPE propellant′s equilibrium humidity is very low,and the propellant can absorb humidity slightly in 11% RH condition. Humidity aging rate is relative to exposed surface area and scale of specimens. The mechanical property loss resulting from short-term humidity aging can be recovered mostly by dehydration in dry air. Humidity accelerates chemical aging obviously in NEPE propellant at elevated temperature. It suggests that it is necessary to take humidity effects on chemical reactions into account in long-term storage evaluation.

Abstract:In order to study the damage process of NEPE propellant during tensile condition,the micro-structure of NEPE sample was observed by in situ SEM. The results show that the interphase dewetting and crack are first founded around big grains. And the binder is pulled into silk shape. Then the crack in NEPE propellant extends through the big grains and collects into macro-crack. On the other hand,the stress distribution in grain-binder unit was also analyzed by finite element method. The analysis shows that the effective stress in big grain-binder unit is much greater than that of small grain-binder unit. So,the main damage model of NEPE propellant during tensile process is interphase damage between big grain and binder.

Abstract:Cryogenic solid propulsion(CSP) technology is a comprehensive technology of solid propellant and liquid propellant. The most important advantages of CSP are its simple structure,high reliability,high energy level and low environmental hazard. The research development of CSP at home and abroad on performance,composition,grain forms and principle motor fire test was introduced,and the future trend of CSP was to further increase its storable and usable temperature and energy level by different means.

Abstract:Molecular imprinting is a promising technology in molecular recognition. Beaded molecularly-imprinted polymers(MIPs) were synthesized by using suspension polymerization methods. MIPs were packed into a flash chromatograph column to simulate adsorptive reactor,performance parameters obtained can be applied for scale-up experiment.

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