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Abstract:To meet the intrinsic requirement for nuclear weapons safety, the insensitive high explosive (IHE) was proposed by US military and 11 kinds of identification tests for IHEs and 5 kinds for IHE components were established further. However, with the development of HEs, the simplified classification of explosives into HE and IHE has limited the innovation of new explosives. Meanwhile, there are not strict definitions and assessment standards for low-sensitive, insensitive and sensitive explosives. In this article a more detailed classification with four classes for the main charges regarding the sensitivity is proposed. That is, the class A means insensitive and complies all the 11 requirements of IHE, e.g. LX-17, PBX-9502. The class B means they are quasi-insensitive and complie 9-10 the requirements of IHE, e.g. LLM-105 based PBX. The class C means low-sensitive, e.g. PBX-9501. And the class D means sensitive, e.g. PBX-9404. It is also proposed that the concepts of insensitive initiators, primary and booster explosives.

Abstract:Nanothermites can be used as the propellant of MEMS-based microthrusters. Addition of energetic binder can enhance the propulsion performance of nanothermite. In this work, nitrocellulose(NC) and polyvinylidene fluoride(PVDF) were chosen as the binder, and the mixtures were prepared by electrospray mixing process. Based on both Chemical Equilibrium and Application(CEA) software calculation and experiments, the influences of fuel/oxide equilibrium ratio (ϕ) and the content of binding agents on propulsion performance were systematically studied, while the results were compared with propulsion performance of the mechanically mixed nanothermites. Results show that nanoparticles were more uniformly dispersed in the electrospray mixed nanothermite than the mechanically mixing case. The calculated optimum ϕ of Al/CuO was 0.9, while the optimal tested ϕ was 1.8. Specific impulse of the mixture reaches 250.2 m·s^-1, by increase of 8.0% for 2.5% NC in comparison with the binder-free Al/CuO. The addition of PVDF reduces the tested specific impulse. The decomposition products of binder separate nanoparticles and increase the characteristic mass transport length of the condensed phase reaction, leading to a distinctly increase in combustion duration, from 2.9 ms to 87.8 ms.

Abstract:To analyze the failure mechanism of an aerospace type of magnesium-aluminum fuel-rich propellant, the component, thermal decomposition rule and ignition performance at atmospheric pressure of the fuel-rich propellant were tested by micro morphology analysis, X-ray diffraction(XRD), thermal analysis and high-speed photography and other detection means. The results show that ammonium perchlorate(AP) in the propellant after moisture absorption is agglomerated and Mg(OH)₂ is formed by the reaction of product after Mg oxidizing with water after moisture absorption. Before moisture absorption, only crystal transition and thermal decomposition with mass loss of AP happen before 420 ℃. Thermostability decreases after moisture absorption, and mass loss begins at 90 ℃. There are four decomposition steps before 420 ℃: evaporation of water, thermal decomposition of Mg(ClO₄)₂ and decomposition AP and Mg(OH)₂ propellant before moisture absorption is able to burn stably after ignition by electric igniter under atmospheric pressure, while propellant after moisture absorption cannot be ignited. Analyses believe that the cause of the failure of the propellant ignition is the AP agglomeration and reducing of active magnesium content, therefore, the priority attention and regular sampling monitoring for magnesium-aluminum fuel-rich propellant stored in humid environment should be applied.

Abstract:Oxalydihydrazinium dinitrate was synthesized via substitution, neutralization reactions using diethyl oxalates and hydrazine hydrate as starting materials with a total yield of 97%. The structure of OHDN was characterized by IR, ¹H NMR, ¹³CNMR, ¹⁵N NMR and elemental analysis. The hydrolysis reaction of oxalydihydrazide was thoroughly studied in dilutenitric acid, and the hydrolyzate are conformed to be oxalic acid and hydrazinium nitrate, and the optimized reaction conditions of OHDN are found to be as follows: reaction temperature 40 ℃, reaction time 2 h. Moreover, the chemical stability of OHDN in water was investigated, showing poor stability at high temperature and good stability at room temperature.The single crystal of OHDN·2H₂O was obtained and its crystal belongs to orthorhombic system, space group is P2(1)/n, a＝0.4639(13) nm, b＝1.0992(3) nm, c＝1.0570(3) nm, V＝0.5301(2) nm³, Z＝2, D_c＝1.755 g·cm^-3, F(000)＝292, R₁=0.0855, wR₂=0.0895.

Abstract:To explore the effect of crude ammonium perchlorate (AP) crystal′s surface defects on the combustion and mechanical properties of HTPB propellant, the crystal morphologys of two kinds of crude AP (40-60 mesh (Ⅰ), 100-140 mesh (Ⅲ)) were observed by scanning electron microscope(SEM), and the effects of crude AP′s morphology defects on burning rate, pressure exponent and mechanical properties of HTPB propellant were studied. The results show that there is little effect of crude AP′s morphology defects on the burning rate and pressure exponent of HTPB propellant′s low-pressure section (3-12 MPa), whereas a noticeable effect on those of its high-pressure section (12-20 MPa). The burning rate of high-pressure section expands the scope from 11.27-13.93 mm·s^-1 to 11.28-16.35 mm·s^-1 and the pressure exponent also increases from 0.40 to 0.70 when the morphology defects appear on the surface of crude AP crystals. The results also show that crude AP′s morphology defects have little effect on the mechanical properties of HTPB propellant.

Abstract:To improve the energy levels of of energetic Pb(Ⅱ) complex of 2, 6-diamino-3, 5-dinitropyridine-1-oxide [ANPyO Pb(Ⅱ)] and obtain the safety and thermal decomposition characteristic parameters of ANPyO Pb(Ⅱ), energetic complex ANPyO Pb(Ⅱ) was synthesized using ANPyO and lead acetate as raw materials, N, N-dimethylformamide(DMF) as solvent. Its structure was characterized by infrared(IR) spectroscopy, elemental analysis and X-ray photoelectron spectroscopy(XPS). Its impact sensitivity and friction sensitivity were tested. The thermal decomposition behavior of the complex was studied by differential scanning calorimetry-thermogravimetry(DSC-TG) at the different heating rate, the apparent activation energy and thermodynamic parameters for thermal decomposition reaction of the complex, and thermal safety parameters of the complex were calculated by Kissinger′s formula, Ozawa′s formula, thermodynamic reaction formula and Zhang-Hu-Xie-Li formula, respectively. The results show that the molecular formula of the complex is Pb(C₅H₃N₅O₅). Impact and friction sensitivity of the complex are 238 cm and 0, respectively. The thermal decomposition process of ANPyO Pb(Ⅱ) in the temperature range of 25-500 ℃ consists of one endothermic melting peak and one exothermic decomposition peak, corresponding peak temperatures are 265.0 ℃ and 332.6 ℃. The apparent activation energy for the thermal decomposition reaction of Pb-ANPyO obtained by Kissinger method and Ozawa method is 202.42 kJ·mol^-1 and 197.40 kJ·mol^-1, respectively. The entropy of activation, enthalpy of activation, free energy of activation of the exothermic decomposition reaction are 149.5, 197.7 kJ·mol^-1 and 112.1 kJ·mol^-1, the critical temperature of thermal explosion and self-accelerating decomposition temperature of the complex are 586.6 K and 572.4 K, respectively.

Abstract:Oxidation system of H₂O₂-UV-O₃ to oxidize the unsymmetrical dimethylhydrazine(UDMH) waste water was established. Using the removal efficiencies of UDMH and chemical oxygen demand(COD) as the detection indexes, the main factors affecting the reaction and the optimal technological conditions were determined through an orthogonal experiment. The degradation efficiencies of four systems: O₃ system, UV-O₃ system, UV-H₂O₂ system and H₂O₂-UV-O₃ system were compared. The variation law of intermediate products was explored preliminarily. Results show that: the removal efficiencies of UDMH and COD in UDMH waste water(mass fraction, 1%) can reach up to 99.99% and 99.30%, respectively in the following conditions: air blows in hydrogen peroxide at pH 9.0 for 24 h, ozone addition rate is 19.6 mg·L^-1·min^-1, molar ratio of hydrogen peroxide to UDMH is 5:1, the ultraviolet type is VUV+UV-C, the reaction time is 1.5 h.

Abstract:A novel green initiating explosive-dipotassium 5, 5′-bis(tetrazole-1-oxide)(BTOK) was synthesized using 1H, 1′H-5, 5′-bistetrazole-1, 1′-diolate(BTO) as starting material. The single crystal of target compound was cultivated by the slow evaporation method, and its crystal structure was determined by X-ray single crystal diffraction. The thermal decomposition behavior of BTOK was investigated through DSC and TG-DTG technologies. Its 5 s explode temperature, impact sensitivity, friction sensitivity and 50% fire energy were measured. Results show that the K⁺ and BTO^2- form a dissymmetrical structure; in different layers, they are alternately arranged and connected with each other, forming a three-dimensional network structure. BTOK has a good thermal stability with a decomposition temperature beginning at 307 ℃ and its exothermic process has obvious primary explosive characteristics. For BTOK, the 5 s explosive temperature is 321 ℃, the friction sensitivity of BTOK is 56%, under the condition of 70°, 1.23 MPa, the impact sensitivity (H₅₀) is 22.5 cm, with the drop hammer of 800 g and the 50% fire energy of electrostatic spark sensitivity is 0.21 J.

Abstract:A high oxygen balance compound-tetranitroacetimidic acid(TNAA), was synthesized via concentrated nitric acid nitrification and organic solvent extraction using 1, 1′-diamino-2, 2′-dinitroethene(FOX-7) as raw material. The yield and purity of TNAA obtained by four kinds organic solvents (dichlormethane, trichoromethane, tetrachloromethane and ethyl acetate) were compared. The thermal behavior of TNAA was studied by DSC and TG. Results show that dichloromethane is determined as the best extraction solvent and its yield and purity are 95.0% and 99.4%, respectively. At a heating rate of 10 K·min^-1, the initial temperature, peak temperature and melting enthalpy of melting endothermic peak of TNAA are 84.8 ℃, 87.8 ℃ and 61.7 J·g^-1 respectively, the initial temperature, peak temperature and decomposition heat of exothermic decomposition peak are 117.7 ℃, 131.4 ℃ and 934.8 J·g^-1, respectively. The apparent activation energy (E) and pre-exponential constant (A) of thermal decomposition reaction obtained by Kissinger method are 124.7 kJ·mol^-1 and 10^16.1 s^-1, respectively. The self-accelerating decomposition temperature (T_SADT), critical temperature of thermal explosion (T_b), and thermodynamic parameters ΔH^≠, ΔS^≠ and ΔG^≠ of thermal decomposition reaction of TNAA at T=T_p are 102.3 ℃, 112.2 ℃, 121.5 kJ·mol^-1, 61.2 J·K^-1·mol^-1 and 98.0 kJ·mol^-1, respectively.

Abstract:Thermal decomposition behavior of 3, 3′-diamino-4, 4′-azoxyfurazan(DAOAF) was studied by TG-DTG and DSC, and the kinetic parameters for thermal decomposition of DAOAF were calculated by Kissinger method and Flynn-Wall-Ozawa method. The specific heat capacity of DAOAF was determined using continuous specific heat capacity modes of a DSC apparatus. According to the relationship between specific heat capacity and thermodynamic functions, the enthalpy, entropy, Gibbs free energy increments of DAOAF from 253 K to 373 K, relative to the standard temperature 298.15 K, were calculated. Results show that DAOAF is an energetic material decomposing with melting. The average activation energy (E) and pre-exponential factor (A) are 152.23 kJ·mol^-1 and 10^12.53 s^-1, respectively. In the range of 253-373 K, the specific heat capacity (c_p) versus T relationship can be fitted into a simple equation: c_p(J·g^-1·K^-1)=0.00303T+0.17235. The standard molar heat capacity of DAOAF is 228.05 J·mol^-1·K^-1 at 298.15 K.

Abstract:To refine the hexanitrostilbene(HNS), nanometer HNS explosive with average particle size of 94.8 nm was prepared by a high energy ball milling method. The characteristics and analysis of the HNS sample were performed by scanning electron microscopy(SEM), X-ray diffractometry(XRD), infrared(IR) spectroscopy, X-ray photoelectron spectroscopy(XPS), DSC-IR analysis and 5s explosion temperature. Results show that after ball milling, the micro morphology of the explosive is nearsr-pherical, and the particle reveals a normal distribution. The mechanical ball milling action does not change the original crystal form, molecular structure, and surface elements of HNS, showing that mechanical milling is a kind of reliable method for fabrication of nanometer HNS.The apparent activation energy of thermal decomposition of nanometer HNS is 12.4 kJ·mol^-1 higher than that of raw HNS, indicating that the activation of nano HNS molecules requires a higher energy. After heating, nanometer HNS decomposes into a large number of CO₂ and a small amount of H₂O, while the N element is present in the non polar N₂ molecule. The 5 s explosion temperature of nanometer HNS is 12.2 ℃ higher than that of raw HNS, meanting than the nanometer HNS has lower thermal sensitivity.

Abstract:To improve the mechanical properties and decrease the mechanical sensitivities of polymer bonded explosives(PBXs), PBXs with 100/0, 95/5, 90/10, 80/20-micrometer/nano-RDX particle gradations were prepared by the solution-water slurry method. Their apparent morphologies were observed with an optical microscope and the mechanical sensitivities, mechanical properties and detonation velocities etc. performances were measured. Results show that the molding powder particles of PBXs with micrometer/nano-RDX particle gradations are smaller and the samples reveal in ball-like particles with regular morphology. PBX prepared with 5% nano-RDX and 95% micrometer-RDX has the best properties, compared with micrometer-RDX based PBX, and the impact sensitivity of PBX with 5% nano-RDX and 95% micrometer-RDX decreases from 44% to 12%, friction sensitivity decreases from 24% to 4%, compression strength increases from 5.55 MPa to 6.57 MPa, tensile strength increases from 0.66 MPa to 0.77 MPa, shear strength enhances from 1.76 MPa to 1.96 MPa, and detonation velocity increases from 8033 m·s^-1 to 8186 m·s^-1.

Abstract:In order to study the thixotropic properties of casting aldol based polymer bonded explosive, the effect of RDX gradation and content of RDX particles on the thixotropic properties of the slurry was explored by a thixotropic loop method. The area of hysteresis loop was used to characterize the thixotropic extent. Results show that the slurry system is a pseudoplastic fluid. The slurry with different RDX gradation has different degree of thixotropy. The higher the number of RDX gradation or the larger the RDX particles, the smaller the thixotropy of slurry. The higher the content of small particles, the greater the influence of gradation of large and middle particles on the decreasing extent of thixotropy of slurry. Thixotropic extent of the slurry reveals a positive correlation with the content of small RDX particles, and a negative correlation with the content of large RDX particles.

Abstract:To improve the explosion energy of nitric ester explosive, boron-containing hydrogen-storage-alloy (Mg(BH_x)_y) was added into nitric ester explosive. The explosion energy and after burning effects of nitric ester explosive with Mg(BH_x)_y were studied by underwater explosion test and explosion test in air. Results show that Mg(BH_x)_y can significantly improve the explosion energy of nitric ester explosive. In explosion test in air, Mg(BH_x)_y is decomposed, and the decomposition products are involved in the detonation reaction. In underwater explosion test, after adding Mg(BH_x)_y, the explosion energy of the nitric ester explosive is increased by 17.56%, and the nitric ester explosive with Mg(BHx)y has an obvious after burning effect.

Abstract:To determine the effect of sintering temperature, ratio and particle size on the reaction phenomenon of Al-Teflon under quasi-static compression, the quasi-static compression test of Al-Teflon was conducted using an universal testing machine and the stress-strain curves and reaction ratio data of test specimen under the influence of sintering temperature, ratio and particle size were obtained. The micro morphology of Al-Teflon was analyzed by a scanning electron microscope(SEM). Results show that the sintering temperature, equivalence ratio and particle size can affect the mechanical behavior of Al-Teflon, change the deformation of material and crack formation mode and affect the excitation of the initial reaction under quasi-static compression. At the same time, the ratio affects the completeness of reaction, an incomplete reaction phenomenon happens when the ratio deviates from the chemical equilibrium ratio, and the reaction intensity and reaction ratio increase with decreasing the Al particle size. The material-process range of Al-Teflon reaction occurring under the quasi static compression is that the sintering temperature is between 320 ℃ and 370 ℃, Al mass fraction is between 16% and 36%, and the particle size of Al powder is less than 12-14 μm.

Abstract:To study the effect of high temperature blast hole on the explosion power of water bath protected emulsion explosive, the enviroment temperature of protected emulsion explosive in high temperature blast hole were simulated by 100 ℃ water bath heating and the underwater explosion parameters were caculated and obtained through underwater explosion experiments. Results show that the detonation velocity, shock wave impulse, specific shock wave energy, specific bubble energy and total energy of emulsion explosive decrease with the increase of water bath heating time. In which, the specific bubble energy and total energy of emulsion explosive decrease in approximately linearly with the increase of water bath heating time, whereas, the effect of increase of water bath heating time on the proportion of specific bubble energy in total energy is smaller and the proportion remains at about 65%.

Abstract:To study the composite interference performance of chopped carbon fiber (CF) clouds to millimeter wave and infrared, the test platform was built. The 1.5 mm and 4 mm CF explosion dispersion experiments were carried out under the static wind condition. The process of forming explosion dispersion clouds was investigated. The interference performance of clouds to 3 mm wave、8 mm wave and 8-14 μm infrared was measured and analyzed. The results show that chopped CF can be effectively dispersed by explosion, and the stable smoke clouds can be formed under the conditions of experimental bomb structure and loading parameters, revealing an excellent composite interference performance to the millimeter wave and infrared. The maximum attenuation to the millimeter wave and infrared is more than 95%. The effective effect time to 3 mm wave(one-way attenuation decibels≥5.2 dB)is not less than 1 min, and the time to 8 mm wave can reach more than 30 s. The effective obscuring time to infrared target (attenuation rate≥85%) is more than 20 s, and the change in CF length has a significant effect on the millimeter wave interference performance.

Abstract:New material is the basis of the development of solid propellant. Among them, the research and development of new energetic materials and combustion catalysts have important significance for improving the properties of solid propellants. Research progresses of metal organic frameworks (MOFs) in heterogeneous catalysis and energetic materials are systematically introduced. It is pointed out that MOFs have higher activity in catalyzing the oxidation reactions of alkanes, alkenes, alcohols and CO, and thus possess ability of catalyzing the propellant combustion reaction. The metal oxides in-situ formed in the combustion process of propellant can also promote the combustion of propellant. MOFs with excellent energy performance and safety performance can be obtained by introducing the high nitrogen content ligands, changing the composition and structure of energetic ligands and their coordination modes with metal ions can effectively tune its energetic performance. Considering that designing and synthesizing the efficient MOFs catalyst used in solid propellant combustion, exploring the reaction mechanism of MOFs in combustion process of propellant, revealing the effect of composition, structure of energetic groups and coordination modes with metal ions on the energetic performance of MOFs may be the research focus in the future.

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