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Abstract:Based on the character of near-half-cylindrical linear forming LEFP(linear explosive formed projectile), the characteristics of impacting initiation of LEFP on charge warhead with shell was studied. The dynamically intercepting impact test of LEFP formed by endpoint initiation way on shaped charge warhead with diameter of 82 mm was performed. The structure failure process of warhead was observed by a high-speed video camera. The numerical simulation model of LEFP shelled charge was established using ANSYS/LS-DYNA simulation software. Simulation analyses to intercept the process of impacting charge with shell under the conitions of forming process of LEFP, different blasting height and different initiation ways was performed. Results show that all the charge with shell measured are initiated. The average peak pressure of explosive by center line initiation is 1.17 times higher than that of explosive by endpoint initiation. LEFP has the possibility as damage element for an active defense system of armored vehicle or other air defense anti missile technology.

Abstract:LS-DYNA software was employed to investigate the asymmetric collision of detonation wave, empennage formation and velocity of explosively formed projectile(EFP) which are caused by three-point initiation synchronization error. Meanwhile, the distortion characters of the liner formed by the composite detonation waves were analyzed. Results indicate that the deviation of trigeminal high-pressure and central ultrahigh-pressure area from liner center are attributed to the error of three-point initiation, which lead to the irregularly formation of EFP empennage. It is noted that a better empennage formation can be obtained when the synchronization error is less than 100 ns. In addition, it will decrease the velocity in the horizontal direction and increase the flight stability of EFP with fins when the middle initiation point synchronization error is about half of the max.

Abstract:To improve the damage efficiency of warhead, the fluorine polymer based energetic reactive materials were studied. The formulation of the fluorine polymer based energetic material was improved and a kind of energetic kill element with dimension of Φ26 mm×60 mm was prepared. Experimental study on shock Initiation of simulative warhead was carried out, in which the energetic kill element was confined by a shell with specific structure. The explosion situation after the energetic kill element penetrated into the warhead was observed by high-speed video and the air shock wave overpressure after explosion was measured. The ignition and blasting ability of the energetic kill element to detonate Comp.B and PBX-9404 under different speeds was examined. The static detonation test of Comp.B simulation warhead for comparison was set. Based on the test, through the measurement of air shock wave overpressure after explosion, the comparison and analysis of the equivalent TNT equivalent was performed. Experimental study show that under the penetration speed of 735 m·s^-1, the energetic kill element can detonate the Comp.B warhead. Under the penetration speed of 962 m·s^-1, the energetic kill element can arouse the Comp.B warhead deflagration.

Abstract:To research on the combustion characteristic of polyethylene in high-speed ramjet kinetic energy projectile, the numerical simulation investigation on the integrated flow field of high-speed ramjet kinetic energy projectile was carried out. The difference of flow characteristics when ramjet working or no working was analyzed. Both the combustion and propulsive performance characteristics of polyethylene when ramjet working were analyzed. The results show that when the ramjet is working, the pressure in combustion chamber is uniform and the average pressure of the central axis is about 2.1 MPa. With increasing the axial distance x, the flame front closes to solid fuel surface at first, and then gradually keeps away from solid fuel surface. With increasing the axial distance x, both the surface temperature and regression rate of solid fuel continue to increase before re-attachment point, the maximum value is reached at the re-attachment point and then decrease. Under the aerodynamic configuration designed in this study, the nominal thrust, net thrust and specific impulse based on fuel produced by high-speed ramjet kinetic energy projectile are 250 N, 76 N and 10593 m·s^-1, respectively.

Abstract:To investigate the detonation and safety properties of energetic derivatives of polynitromethylazoxyfurazan, the effects of nitroazoxy, trinitromethylazoxy and fluorodinitromethylazoxy etc energetic groups on the geometric configuration, electrostatic potential distribution, density, enthalpy of formation, oxygen balance, detonation velocity, detonation pressure, bond dissociation energy and impact sensitivity of furazan, azofurazan, azoxyfurazan and furazan ether compounds were compared and studied at the B3LYP/6-31G^** basis set level based on B3LYP method of density functional theory.Results show that trinitromethylazoxy and fluorodinitromethylazoxy can greatly improve the density and oxygen balance of furazan derivatives, fluorodinitromethylazoxy can also greatly improve the detonation velocity and detonation pressure of furazan derivatives and has good thermal stability and impact sensitivity.Based on theoretical calculation results of 12 kinds of furazan energetic derivatives, a high energy density compound 3, 3′-bis(fluorodinitromethylazoxy)-4, 4′-azoxyfurazan is selected and its density is 2.019 g·cm^-3, detonation velocity is 9.735 km·s^-1, detonation pressure is 44.90 GPa, characteristic drop height is 36 cm.

Abstract:To investigate the safety of explosive under thermal and impact coupling effect, a 50 kg drop hammer impact test of HMX based PBX with Φ20 mm×8 mm at 20-170 ℃ was performed by a self-designed experimental device.In the experiment, the pressure histories of explosive during the impact process was measured by pressure sensors.The impact ignition process of explosive was shot by the high-speed photography system.The impact response characteristics of PBX explosive at different temperatures were obtained.Results show that the impact safety of forming PBX explosive was closely related to the temperature, the impact safety at 82 ℃ is improved, and the impact safety at 170 ℃ becomes worse significantly.In the temperature range of 20 ℃ to 170 ℃, with increasing the temperature, the impact sensitivity of PBX first decreases and then increases gradually.This is related to the mechanical property changing of PBX explosive occurred at high temperature, and the damage caused by thermal expansion, thermal decomposition, and the phase transition occurrence of HMX and other factors.

Abstract:Ultrafine and spherical ε-CL-20 particles were prepared by the spray and ultrasound-assisted recrystallization device.The morphology, particle size and crystal type of the samples were characterized by scanning electron microscopy(SEM) and X-ray diffraction(XRD).The thermal stability of the samples were analyzed by differential scanning calorimetry(DSC).The apparent activation energy of thermal decomposition reaction and critical temperature of thermal explosion were calculated by Kissinger′s method and Zhang-Hu-Xie-Li′s formula.Their mechanical sensitivity were tested by GJB772-1997 method.Results show that prepared ultrafine CL-20 is spherical particle with size of about 400nm and have a good dispersibility.The crystal type of the ultrafine CL-20 is epsilon(ε).The thermal stability of ultrafine CL-20 is lower than raw material CL-20.The critical temperature of thermal explosion of raw material CL-20 and ultrafine CL-20 is 242.85 ℃ and 241.64 ℃, respectively.The apparent activation energy of raw material CL-20 and ultrafine CL-20 is 156.04 kJ·mol^-1 and 165.11 kJ·mol^-1 respectively.Compared with raw material CL-20, the impact sensitivity of ultrafine CL-20 decreases significantly, the characteristic drop height (H₅₀) increases from 14.98 cm to 31.95 cm, the friction sensitivity of ultrafine CL-20 also decreases, the explosion probability decreases from 100% to 40%.

Abstract:To overcome the incompatible problem of ammonnium dinitramide(ADN) and the isocyanates curing agents, the curing coating research of spherical ADN particles were carried out usinng glycidyl azide polymer(GAP)/ bis-propargyl-succinate(BPS) crosslinked polymers as a coating material via 1, 3 dipolar cycloaddition reaction.The surface element composition and hygroscopicity of the coated ADN-prills were investigated by scanning electron microscopy with energy dispersive spectrometer (EDS) and dynamic hygroscopic analytical method respectively.Results show that compared with the GAP/hexamethylene diisocyanate biuret curing agent (N-100) crosslinked polymers, the GAP/BPS crosslinked polymers exhibited better compatibility and coating effect with ADN, and the saturated hygroscopicity of coated ADN is only 0.78%.

Abstract:Ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF₆]) was used as a plasticizer of acrolein-pentaerythritol resin (123 resin). The effect of [BMIM][PF₆] content under the condition of 0~10% on the plasticizing properties of 123 resin was studied. The comprehensive mechanical properties of cured 123 resin were studied by an universal testing machine and a dynamic mechanical analyzer (DMA) respectively.Results show that [BMIM][PF₆] can effectively improve the flowability of prepolymer of 123 resin, the effect is better than that of diethyl phthalate (DEP) and addition of 10% [BMIM][PF₆] can make the viscosity of 123 resin prepolymer at 50 ℃ reduce to 185 mPa·s. The more the [BMIM][PF₆] content, the greater the elongation at break and the lower the tensile strength of 123 resin cured products, and the elongation at break and tensile strength of 123 resin containing 10% [BMIM][PF₆] are 14.2% and 38.2 MPa, respectively. The glass transition temperature decreases and tenacity increases of 123 resin cured products with the increasing of [BMIM][PF₆] content in 123 resin.

Abstract:The catalyst A336/MWCNT was prepared by an ultrasonic method through grafting methyl trioctyl ammonium chloride (A336) on the surface of multiwalled carbon nanotubes(MWCNT).Its structure was characterized by Fourier transform infrared spectroscopy(FTIR) and thermal gravimetric analyzer(TGA).The reaction performance of catalyzing the hydroxyl-terminated polybutadiene(HTPB) to synthesize epoxidized hydroxyl-terminated polybutadiene(EHTPB) was investigated.Results show that A336 is successfully grafted on the surface of MWCNT through the coordination effect of amino group and carbonyl group, the synthesized A336/MWCNT has good catalytic activity, high stability and strong regioselectivity.At 4 h for the catalytic reaction, the epoxidation degree of HTPB can reach 25% and has no significantly decreasing after the catalyst reused for three cycles.The reaction selectivity for trans 1, 4—C＝C structure in HTPB increases by 14.4% compared with the A336.

Abstract:To prepare dinitramide salt product safely and efficiently, ammonium sulfamate as precursor was nitrated at low temperature with HNO₃/H₂SO₄ mixed acid and the reacting solution was neutralized with inert solution containing N-guanylurea to form N-guanylurea dinitramide(FOX-12).Then potassium dinitramide(KDN) and ammonium dinitramide(ADN) were prepared by an ion-exchange reaction.The characterization and performance test of FOX-12, KDN and ADN were performed by elemental analysis, IR, density, DSC and sensitivity test.The results show that the hydrolysis temperature in the experimental process is maintained between 30 to 45 ℃, realizing the enlargement synthesis technology of FOX-12, KDN and ADN.The characterization data are in agreement with literature values.The purity of crude product is greater than 98%.The melting points of FOX-12, KDN and ADN are 212, 128 ℃ and 92 ℃, respectively.The sensitivities of FOX-12 and KDN are lower than that of RDX, but the sensitivity of ADN is comparable to that of RDX.

Abstract:To solve the problem on end point of curing encountered in engineering application, the curing reaction kinetics of hydroxyl-terminated polybutadiene(HTPB) type bonding system used for polymer bonded explosive(PBX) wss studied by isothermal and non-isothermal differential scanning calorimetry(DSC) through the simulation of n-order reaction kinetic model according to Kissinger method and Crane method. Results show that the apparent activation energy, reaction order, pre-exponential factor and curing reaction heat for curing reaction of HTPB/TDI bonding system are 54.61 kJ·mol^-1, 0.87, 192.80 s^-1 and 482.87 J·g^-1, respectively. Autocatalytic phenomenon exists in the curing reaction process of the system. After adding the dibutytin dilaureate (T12) catalyst, the curing reaction rate of the bonding system increases and the reaction temperature decreases. The function relation between the curing temperature and the curing time is fitted and obtained. Calculated curing time is about 3.91 days when the curing temperature is 60 ℃, which is consistent with 4-6 days in the practical engineering applications.

Abstract:The effect of the burning rate catalysts Fe₂O₃, CuO, Cr₂Cu₂O₅, PbCO₃, C₆H₅O₇Pb, lead salt 3-nitro-1, 2, 4-triazole-5one (NP), and carbon black(CB) on the thermal decomposition properties of GAP-based ETPE were investigated by TG and DSC. The results show that several burning rate catalysts have a great influence on the thermal decomosition of of azide groups in the GAP-based ETPE, in which, CuO and Cr₂Cu₂O₅ make the thermal decomposition peak temperature of azide groups in GAP-based ETPE decrease by 21.9 ℃ and 13.6 ℃, respectively, but Fe₂O₃, PbCO₃, C₆H₅O₇Pb, NP and CB make the thermal decomposition peak temperature of azide groups in GAP-based ETPE increase by 1.7, 2.6, 1.6, 1.0 ℃ and 1.1 ℃, respectively. CuO, Cr₂Cu₂O₅, C₆H₅O₇Pb and CB make the apparent decomposition heat of azide groups in GAP-based ETPE increase by 75.5, 84, 43.4 J·g^-1 and 103.1 J·g^-1 respectively. However, Fe₂O₃, PbCO₃ and NP make the apparent decomposition heat of azide groups in GAP-based ETPE decrease by 137.9, 58.8 J·g^-1 and 47.3 J·g^-1.respectively. After the comprehensive comparison, considering that CuO and Cr₂Cu₂O₅ make the thermal decomposition peak temperature of azide groups in GAP-based ETPE decrease and the apparent decomposition heat increase, they are ideal catalysts of catalyzing the thermal decomposition of the GAP-based ETPE.

Abstract:Two kinds of poly(glycidyl nitrate)(PGN) binders with molecular weight of about 3000 were synthesized via cationic polymerization using glycidyl nitrate(GN) with purity of more than 99.5% as raw material. Their structures were characterized by infrared spectroscopy(IR), nuclear magnetic resonance(NMR) and gel permeation chromatograph(GPC). The main properties of PGN were tested. The curing reaction of PGN with common isocyanates, polyaryl polymethylene isocyanate(PAPI), modified hexamethylene polyisocyanate(N-100), toluene diisocyanate(TDI), dicyclohexyl methane diisocyanate(HMDI) was studied. Results show that the curing reaction of PGN can performed rapidly with PAPI, N-100, TDI and HMDI etc. under the action of catalysts dibutyltin dilaurate(DBTDL) or triphenyl bismuth(TPB), and the cured samples have no obvious decrease in Shore A hardness after storeing at 60 ℃ for 60 days.

Abstract:Pin broken appears in process of extrusion of 19-hole propellant and products are hard to be shaped when the viscosity of flow is high. This study simulated the forming process of propellant by the finite element method to solve this problem. On the basis of simulation results, effects of the compression ratio, the length of forming section and structure of pin holder on the distribution of stress and velocity of propellant flow were analyzed. The compression ratio of the optimized die is 4.25, the forming length is 26.0 mm, and the pin holder is optimized to increase the axial flow propellant. The results show that, after optimization, the maximum pressure in the flow channel reduces by 40.45%, the radial force on the outermost die pins reduces by 37.45%, the maximum radial velocity of the fluid in compression section decreases by 66.98%. The components distribute evenly, the propellant surfaces are smooth and the holes are in good distribution in propellants which are extruded by the new die. The constant volume combustion experiment confirms that the 19-hole propellants burn stability and the progressive combustion is excellent.

Abstract:3, 4, 5-Trinitro-1H-pyrazole(TNP) as the only full-carbon nitrated pyrazole-based compound, has the advantages of high density, high energy and low sensitivity and broad application prospcts in the field of energetic materials.In this paper, synthesis, properties and applications of TNP and its covalent derivatives and energetic ionic salts(including metal salts and nonmetal salts) were reviewed.The molecular design of energetic compounds of TNP as skeleton was discussed from the point of view of the molecular level.Considering that further research of such energetic compounds should focus on the following directions:the new synthesis methods and process optimization of TNP; the study on the synthesis and properties of 1-amino-3, 4, 5-trinitropyrazole(ATNP) and 1, 3, 4, 5-tetranitropyrazole; the molecular design and synthesis of novel energetic compounds combined TNP with rich-nitrogen groups; the appliced research of TNP and its derivatives.

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