Abstract:

Abstract:To improve the energy utilization ratio of explosives in explosive welding, the honeycomb aluminum structure emulsion explosive and the multidimensional constraint charge way of cover plate arranged on the upper end of honeycomb aluminum structure emulsion explosive were used. The multidimensional constraint of honeycomb structure and cover plate weakens the effect of rarefaction wave in air on the detonation of explosive, reduces the critical diameter of explosive detonation and improves the work ability of explosive driving flyer plate.Taking 304 stainless steel and Q235 steel as flyer plate and base plate respectively, the contrastive explosive welding tests of multidimensional constraint charge and bare charge of ordinary emulsion explosive were carried out. The explosive welding window and the influence of the cover plate on the impact velocity of the flyer plate were theoretically analyzed by Gurney model. Results show that compared to the existing explosive welding technology, the bonding quality is obviously improved and the consumption of explosives is reduced by 50% and the energy utilization ratio of explosives is significantly improved. The impact velocity of the flyer plate increases with the increase of the quality of the cover plate, but the increase rate decreases. In addition, the explosive welding window is obtained and the welding quality is predicted, and the experimental results are in good agreement with predicted ones.

Abstract:To study the damage efficiency of axial-expanding directional warhead, AUTODYN software was systematically used to analyze the influence of the expansion angle and the initiation position on the fragment performance of axial-expanding directional warhead. The influence law of the axial expansion angle and the initiation position of warhead on the formation of fragment mass distribution, flying dispersion velocity and flying dispersion angle was obtained. Results show that the velocity of the forward explosively formed projectile (EFP) decreases with the increase of the axial expansion angle, while increasing the length-diameter ratio of EFP, taking the wing-diameter ratio of about 4.2, increasing the axial expansion angle of the warhead can improve the percentage of effective fragment mass, and the maximum flying dispersion velocity of the fragment appears at about 33.33% from the initiation end. The percentage of effective fragment of warhead at the outer side of the charge is up to 67.57%. Selecting the axial expansion angle of the warhead as about 60°, and the initiation point located at the outer side of the charge, can realize the effective damage function of directional and convergent strike of axial-expanding directional warhead.

Abstract:To study the effect of multi-point initiation circuit charge on detonation wave output synchronicity and initiation capability, a rigid three-point synchronous initiation circuit was designed using ultrafine Octogen (HMX) as main explosive, nitrocellulose (NC) as binder, 95/5-HMX/NC as groove booster charge. The synchronicity error of initiation circuit at different charge density was theoretically analyzed and experimentally measured. The groove press loading charge technique was compared and tested. The booster explosive was characterized, the detonation performances related to initiation circuit were tested and the initiation circuit charge structure was optimized. Results show that increasing circuit charge density can increase the initiation reliability and reduce the synchronicity error. The synchronicity error of initiation circuit decreases from 300 ns to 150 ns when the charge density increases from 1.17 g·cm^-3 to 1.47 g·cm^-3. Taking pressed JH-2 cylinder charge as output charge and ultrafine HMX/NC as groove booster, use of groove press loading charge technique can make the detonation wave output synchronicity of synchronous initiation circuit as about 100 ns.

Abstract:1-Nitroso-3, 5, 7-trinitro-1, 3, 5, 7-tetraazacyclooctane (MNX) is an intermediate in the production of 1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetraazacyclooctane (HMX) from 3, 7-dinitro-1, 3, 5, 7-tetraazabicyclo[3.3.1]nonane (DPT) by nitrolysis. To study the mechanism of HMX formation from DPT and fuming nitric acid, formaldehyde was added into the reaction. A new process of preparing MNX by reaction of DPT in red fuming nitric acid (HNO₃/N₂O₄)was investigated. The influence of reaction temperature, loading amounts of nitric acid, N₂O₄ and NH₄NO₃ on the reaction was investigated. The optimum reaction conditions were determined by an orthogonal experiment. The sensitivities of MNX were measured by GJB772A-97 method and WJ/T9038.3-2004 method. Results show that formaldehyde can promote the reaction of DPT and fuming nitric acid to form MNX and the nitrosolysis reaction mechanism in the redox of DPT in nitric acid is proposed.The yield of MNX is 83.5% under the optimized reaction conditions of molar ratio of N₂O₄ to DPT as 1 :1 and molar ratio of NH₄NO₃ to DPT as 2.5 :1 at -25 ℃. Its impact sensitivity and electrostatic sensitivity of MNX are lower than those of RDX and HMX, while the fricon tisensitivity is between RDX and HMX.

Abstract:4-Nitropyrazole(4-NP) was synthesized via a "one-pot two steps" method using pyrazole as raw material in a fuming nitric acid (w=98%)/20% oleum system. The target product was characterized by IR spectrometry, nuclear magnetic resonance spectroscopy, high resolution mass spectrometry and elemental analysis. The single crystal structure was determined by X-ray single-crystal diffractometer The effect of material ratio, reaction temperature, and reaction time on the yield of product was studied. Results show that the best synthesis process is n(fuming nitric acid):n(oleum):n(concentrated sulfuric acid):n(pyrazole)=1.5:3:2.1:1, reaction temperature 50 ℃, reaction time 1.5 h, the highest yield is 85%. The single crystal structure of 4-NP belongs to triclinic crystal system, its space group is P-1 with cell paramaters of a=8.0329(11) Å, b=9.6305(8) Å, c=9.9036(8) Å, α=74.393(7)°, β=81.560(9)°, γ=83.196(9)°, V=727.40(13) ų, Z=6, ρ=1.549 mg·mm^-3, μ=0.132 mm^-1, F(000)=348.

Abstract:In order to understand comprehensively the thermal decomposition behavior of dihydrazinium salts of bis(5-amino- 1, 2, 3, 4-tetrazolium) (Hy₂BTA), thermal decomposition curves at different heating rates and the types of decomposition gas products and their content change of the compound were measured by combined method of thermogravimetry-differential scanning calorimetry-Fourier transform infrared spectroscopy-mass spectrometry (TG-DSC-FTIR-MS). Results show that the thermal decomposition of Hy₂BTA includes two endothermic processes and two successive exothermic processes with temperature increasing, corresponding to the broken of first ionic bond in Hy₂BTA with the expulsion of NH₂NH₂, the tetrazole rings began to release N₂ with the rupture of —N—N— during the break of the second ionic bond in Hy₂BTA, gas products N₂, HN₃, NH₃ and HCN were generated by the cleavage of tetrazole rings and the further decomposition of residual skeleton, in addition, the polymerization of decomposition products and pyrolysis of residual skeleton can be occurred which produce polymer containing nitrogen and HN₃, N₂ and NH₃, respectively. The apparent activation energies of four processes calculated by Kissinger′s method are 115.12 kJ·mol^-1, 193.75 kJ·mol^-1, 334.16 kJ·mol^-1 and 243.40 kJ·mol^-1 respectively.

Abstract:To study the effect of polybutadiene rubber (BR) binder on the performances of RDX-based pressed polymer bonded explosive (PBX), the mass, volume, the vacuum stability, mechanical performances and mechanical sensitivities of grain before and after aging were measured by high temperature accelerated aging test at 71 ℃. The change situation of microstructure, elemental content and chemical environment of the explosive was observed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Results show that after high temperature storage, change rate of volume and mass of grain is less than 1%, and no obvious defects such as crack are observed. The compressive strength increases by 74% and tensile strength increases by 117%. The impact sensitivity decreases from 8% to 4%, and the friction sensitivity decreases from 18% to 8%. The stability of the explosive does not change significantly in the high temperature aging process. The analysis thinks that in the accelerated aging process, due to the instability of carbon-carbon double bond, BR binder in the grain occurs oxidative crosslink, making the crosslinking degree increase, and the softening, spreading and uniform distribution caused by heating make the effect of coating and binding enhance, thereby, the mechanical performance of the explosive is improved and the mechanical sensitivity is reduced.

Abstract:To study the effect of magnesium hydride (MgH₂) on the ignition performance of Al and B mixed system, a new high energy hydrogen-containing ternary metal fuel was prepared by mechanical mixing method using aluminum powder as matrix, boron powder as high energy metal additive, and magnesium hydride (MgH₂) as active metal additive The minimum ignition energy (MIE) of Al, B and MgH₂ was determined by a 1.2 L Hartmann tube apparatus and the MIE of binary metal mixtures (Al-MgH₂, B-MgH₂) under the conditions of different MgH₂ contents and ternary metal mixture Al-B-MgH₂ under the conditions of different boron and MgH₂ contents was compared and studied. Results show that the MIE of Al and MgH₂ is lower, their values of MIE are 80-100 mJ, 5-10 mJ, respectively, the MIE of B is higher, whose MIE is more than 1000 mJ. With the increase of MgH₂ content in the mixture from 10% to 30%, the MIE of Al-MgH₂ and B-MgH₂ reduces from 50-70 mJ and more than 1000 mJ to 10-20 mJ and 480-500 mJ, respectively. With decreasing the boron content in the ternary mixture Al-B-MgH₂ from 25% to 10%, whose MIE also reduces from 700-800 mJ to 20-30 mJ and when the boron content is certain value, the increase of MgH₂ content can significantly decrease the MIE of Al-B-MgH₂ metal mixture. When the content of boron powder is reduced to 10%, the MIE of Al-B-MgH₂ metal mixture powder can be maintained in the range of 20-40 mJ.

Abstract:To study the effect of ratio of silicon carbide to epoxy resin in SiC conductive adhesive on the performances of electrostatic protection, insulation resistance and ignition sensitivity for electric-explosive device, the ratio of silicon carbide to epoxy resin was adjusted, ten kinds of silicon carbide conductive adhesive materials with different proportions were prepared. According to an electrostatic discharge test and a method for measuring insulation resistance prescribed in GJB5309.6-2004 "Test methods for initiating explosive devices", the highest electrostatic protection voltage, the insulation resistance of the foot and shell and the ignition performance parameters for a standard initiating explosive device under the condition that the SiC conductive adhesive is not coated and the SiC conductive adhesive is coated with different proportions were measured. The influence law of SiC conductive adhesive on the performance of electric was obtained. Results shows that when the ratio of silicon carbide to epoxy resin is 1.25:1. the highest electrostatic voltage protection capability of the initiating explosive device reaches 30 kV, and when the test voltage is less than 100 V, it can meet the requirement of insulation resistance value >20 MΩ, at the same time it does not affect the ignition performance of the product.

Abstract:To compare the luminescence effect of different blue light pyrotechnic compositions and explore the new method of optimal design of formulations, the thermodynamic study on six kinds of blue light pyrotechnic compositions was carried out by REAL thermodynamic program. The relationship among the enthalpy of combustion reaction, flame temperature and emitted photon numbers of blue light pyrotechnic compositions was established. The formulation and proportion of blue light pyrotechnic compositions was optimized and selected based on the combustion flame temperature and photon numbers of emitted blue light obtained by calculation. Results show that the combustion temperatures of six kinds of blue light pyrotechnic compositions are 1651-2880 K, which is in accordance with the results calculated by NASA-CEA program. The photon numbers emitted at the maximum wavelenght are 0.02011-0.0435 mol·kg^-1 and the major emitter that produces blue flame is CuCl. With the help of the relationship among the enthalpy of combustion reaction, flame temperature and emitted photon numbers of blue light pyrotechnic compositions, the combustion temperature of the blue light pyrotechnic composites containing KClO₃, 2CuCO₃·Cu(OH)₂ and S is 1651 K. The emitted photon number is 0.0435 mol·kg^-1. The emitted effect of blue light is better in the six kinds of formulations. The optimal proportion of the formulation is KClO₃/2CuCO₃·Cu(OH)₂/S=63/19/18. It provides a new method for the design and optimization of the other light pyrotechnic compositions.

Abstract:To improve the explosion power of traditional emulsion explosives, a kind of emulsion explosive sensized by hydrogen storage glass microspheres was developed. The detonation performances of emulsion explosives with different contents of hydrogen storage glass microspheres were studied by underwater explosion test and brisance test. The specific impulse of explosive brisance was obtained by theoretical calculation. Results show that compared with emulsion explosives with ordinary glass microspheres, the shock wave overpressure peak, shock wave specific energy, bubble specific energy, total energy of the emulsion explosives with 4% hydrogen storage glass microspheres increase by 14.25%, 14.22%, 11.11% and 12.67%, respectively, and its brisance (lead cylinder compression value) increases by 3.03 mm. The shock wave parameters of explosive decrease gradually with increasing the content of hydrogen storage microspheres. The hydrogen storage glass microspheres play a dual role of sensitizer and energetic material in the emulsion explosive. Therefore, a significant increase in the work capacity and brisance of the emulsion explosives sensitized by hydrogen storage glass microspheres is obtained.

Abstract:Hexamethylenetetramine-acetic acid (HA-HAc) solution is an important raw material for preparing Octogen (HMX). In order to rapidly determine the HA content in HA-HAc solution, the temperature calibration model of quantitatively analyzing HA was established by near-infrared (NIR) spectroscopy technology and adding temperature factor. The effect of temperature and spectral pretreatment method on the model was discussed. Results show that temperature will affect the absorbance of the solution, the average relative error of the model with temperature factor is reduced by 81.74%, and the accuracy of the model is improved. The spectral pretreatment can eliminate the interference of external factors to infrared spectrum collection, which is beneficial to improve the accuracy of modeling. The best pretreatment method is the first derivative + Norris-derivative method. The evaluation parameters of the temperature correction model are correlation coefficient R²=0.9997, the root-mean square error of correlation RMSEC=0.0388, the root-mean square error of cross-validation RMSECV=0.0441, and the root-mean square error of prediction RMSEP=0.0350. The standard deviation of model repeatability is 0.0153% and the repeatability of this method is 0.1298%,revealing that the method can be used for fast determination of HA content in HA-HAc solution.

Abstract:Aiming at the problem of low mass transfer efficiency of ozone existed in traditional reactor, the high gravity technology of rotating packed bed (RPB) coupled with advanced oxidation method of O₃/Fe(Ⅱ), (RPB-O₃/Fe(Ⅱ)) was used for deep oxidation degradation of aniline (AN) wastewater. The effects of high gravity factor β, dosage of catalyst Fe(Ⅱ), concentration of O₃, pH value of system and initial concentration of AN on the degradation rate of AN and removal efficiency of total organic carbon (TOC) were studied. The intermediates of AN degradation process were analyzed by liquid chromatograph-mass spectrometer (LC-MS). The degradation mechanism of AN was investigated. Results show that increasing of high gravity factor is beneficial to the deep degradation of AN wastewater. The pH value of the system can affect the direct and indirect reactions of ozonation and the existence form of catalyst Fe(Ⅱ). and the RPB-O₃/Fe(Ⅱ) system broadens the pH range for O₃ use. The increase of ozone concentration is beneficial to improving the efficiency of AN degradation but the utilization efficiency of ozone decreases. When high gravity factor is 100, Fe(Ⅱ) concentration 0.8 mmol·L^-1, O₃ concentration 36 mg·L^-1, pH 3 and initial concentration of AN 200 mg·L^-1, the AN removal efficiency reaches 100% in 12 min, and TOC removal efficiency is 73% in 60 min.The intermediates of AN oxidation degradation process mainly are nitrobenzene, p-benzoquinone, maleic acid and oxalic acid. The possible pathway to deduce the catalytic oxidation degradation of AN by O₃ is described.

Abstract:In order to remove high-strength nitrophenols, heavy metal such as Pb²⁺ and N₃^-, which were highly toxic characteristic pollutants in the wastewater from the manufacture of hybrid initiating explosive such as lead styphnate, lead azide and tetrazene, physico-chemical pretreatment process consisted of internal electrolysis, Fenton, coagulation and sedimentation was developed. The toxicity of the wastewater was efficiently reduced and the biodegradability was efficiently improved. In order to achieve the discharge standard, the bioaugmentation process consisted of anoxic degradation system and biological aerated filter was developed, which was based on the usage of specific functional microbial inoculum. The high-strength organic contaminants in the wastewater after pretreatment could be effectively removed in the bioaugmentation process. The engineering practice showed that wastewater from the manufacture of hybrid initiating explosive could be treated steadily below the discharge standard through the application of the integrated process of physico-chemical treatment and bioaugmentation, with effluent quality met the requirement of "Discharge standard for water pollutants from ordnance industry-initiating explosive material (GB14470.2-2002)". The treatment cost was as low as ￥73.6 per ton wastewater. The integrated process consisted of physico-chemical treatment and bioaugmentation for the treatment of wastewater from the manufacture of hybrid initiating explosive showed significant cost, environmental and social benefit.

Abstract:

Abstract:

Abstract: