Abstract:Energetic compouds based on furoxan ether were a type of important energetic materials with lower melting point, good energy and excellent plasticity. Since 1990s, the type of energetic compounds has been an important research direction in the synthetic fields of energetic materials.In this paper, the synthetic methods of symmetrical and unsymmetrical energetic compouds based on furoxan ether were reviewed. Some representative energetic compounds, such as FOF-1, FOF-2, FOF-11 and FOF-13, were reviewed, and their syntheses, performances and application were introduced in detail. The structures of 11 novel energetic compouds based on furoxan ether were designed, and their physico-chemical properties, detonating performance were calculated by MP3 semi-empirical method, and the results show that calculated densities of two designed compounds exceed 1.90 g·cm^-3, and theoretical detonation velocities are more than 9000 m·s^-1.

Abstract:Capacitive discharge SCB initiation of energetic materials was discussed at different firing voltage levels. Both of SCB are the same resistance and difference mass. The energetic materials are LTNR and PbN₆. For the SCB device, there are three modes of igniting energetic materials, electrothermal ignition, electrical explosive ignition and plasma ignition, respectively. To understand further the behavior of SCB ignition, we measured the critical ignition voltage and ignition time of SCB/LTNR and SCB/PbN₆ device. As a result the critical ignition energy is not only related with energetic materials, but also the comparable mass of the SCB bridge, so there is an optimal design mass about SCB bridge. Besides, the LTNR was more sensitive than PbN₆, however, the burning rate of PbN₆ is higher than that of LTNR.

Abstract:An assembly of exploding foil and flyer for slapper squib was invented. The flyer is a type of heat melting gooey, can integrate the exploding foil at about 230 ℃ to form the assembly. The assembly conquered the difficulty of the 5000V insulation of minitype slapper squib with full metallic shell, improved the ignition reliability and might improve the shelf life of the slapper squib, and had no effect on the output performance of the slapper squib.

Abstract:For applications of porous silicon in energetic materials field, the reactivity of porous silicon/Pb₃O₄ modified by silane coupling agents was studied. The porous silicon used in this work was fabricated by an electrochemical etching technique and modified by KH550, KH560 and KH570, and the 10/90-porous silicon/Pb₃O₄ ignition composition was prepared. The reactive performances of the ignition composition were measured by oxygen bomb, DSC, TG and mass spectrometry. The residues after decomposition and combustion were analyzed by XRD. The results show that: (1) the heats released from samples 2, 3 and 4 modified by silane coupling agents KH550, KH560 and KH570 respectively, are higher than that of sample 1, which is not modified by silane coupling agents, but their temperatures of exothermic peaks are same, showing that the silane coupling agents just affect the kinetic behavior of decomposition reaction of the ignition composition; (2) The values of combustion heat of samples 1-4 decrease in the order: sample 2>sample 3>sample 4>sample 1; (3) the residues of all porous silicon/Pb₃O₄ after decomposition and combustion are PbO and lead silicate, respectively; (4) the KH550, KH560 and KH570, make the stability of the porous silicon in air enhance.

Abstract:A method of evaluating the storage reliability of pyrotechnics based on performance degradation data of accelerated aging test was presented. The relation curve of reliability and the storage time at room temperature was obtained. Results show that the storage life at normal temperature of explosive blot with reliability of 0.999 is 10 years.

Abstract:The silicon type delay composition was prepared by co-precipitation and hand-mixed.Based on the analysis of electron microscopy, EDS spectra and X-ray diffraction, BaSO₄ and little (BaPb) SO₄ were found out and part of silicon and Pb₃O₄ were coated by BaSO₄ during the process of co-precipitation. The delay time and burning rate of the delay compositions were measured by light-sensitive detector. Results show that the average burning rate of the delay composition prepared by co-precipitation is 1.25 mm·s^-1, slower than that of hand-mixed, which is 1.41 mm·s^-1. The delay precision of the delay composition prepared by co-precipitation was better than that of hand-mixed one. The standard deviation of burning rate of the co-precipitation composition is 0.073, and that of the composition prepared by hand-mixed is 0.25.

Abstract:The combustion characteristics of Mg/polytetrafluorethylene (PTFE) were studied with support vector machine (SVM) method, in order to improve the accuracy of combustion characteristics forecasting for the pyrotechnic composition. The predicted values were compared with that of experiments also. The results show that the predicted and experimental values agree with each other, and this method has high accuracy. The prediction maximum relative errors of the combustion velocity, the combustion temperature and the combustion heat are 9.96%, 9.84%, 4.20% respectively.

Abstract:The oblate spherical powder with micro-pores(MOSP)can change the transfer mode of heat and quantity in the process of its combustion, reduce its web thickness and increase its burning surface, so as to achieve the rapid combustion of propellant in weapons. In view of the causes of the hole formation in MOSP, several factors of hole formation were discussed: air, solvent vapor and water. By means of eliminating or weakening the factor of hole formation by water, standing for removing the air bubbles and quick heating respectively, determining bulk density and observing section microstructure of MOSP with a microscope, the mechanisms of hole formation by air and by solvent vapor were confirmed. Results indicate that the air is a tiny factor of hole formation, and can be ignored. The range of pore diameter is from micro/nano to several millimeters, and the pores randomly distribute in MOSP. The solvent vapor is not a factor of hole formation, and the quick heating can not make pores in MOSP, but it can change the bulk density of MOSP along radial.

Abstract:The non-isothermal crystallization of 2, 4-Dinitroanisole (DNAN) in RDX was studies by differential scanning calorimetry. Several kinetics models were used to investigate the crystallization behavior of DNAN. The results show that RDX can reduce the super-cooling degree of DNAN and eliminate self-heating of DNAN crystallization. The crystallization kinetics exponent obtained by Avrami equation is 2.34. The mechanism function g(α) was determined. Ozawa exponent of non-isothermal crystallization (m) is 0.77 from Avrami-Ozawa equations. Activation energy (E_a) of DNAN non-isthermal crystallization is 214.99 kJ·mol^-1 with Hu-Zhao-Gao-Zhao equation.

Abstract:In order to provide better guidance to the preparation of HMX by nitrolysis of 1, 3, 5, 7-tetraacetyl-1, 3, 5, 7-tetrazacyclooctane (TAT), the nitrolysis mechanism was investigated. Two byproducts 1, 5-diacetyl-3, 7-dinitro-1, 3, 5, 7-tetrazacyclooctane (DADN) and 1-acetyl-3, 5, 7-trinitro-1, 3, 5, 7-tetrazacyclooctane (SEX) were obtained by flash column chromatography and were indentified by ¹H NMR, FTIR and elementary analysis. The results reveal that TAT is nitrated in succession to form HMX, and the order of the reaction rate is k₂ > k₁, k₂ > k₃ > k₄.

Abstract:Split Hopkinson Pressure Bar (SHPB) was used to investigate the intrinsic anti-acceleration capability and mechanicalmodel of Lead Azide(LA), Lead Styphnate(LTNR), Tetraammine bis (5-nitrotetrazolato) Cobalt(Ⅲ) Perchlorate (BNCP). Results show that, the intrinsic anti-overload capabilities of LA, BNCP and LTNR are 5000 g, 5000 g, 10000 g respectively. Primary explosive charge suffered a short elasticity deformation, and then the brittle fracture occured.

Abstract:High performance liquid chromatography (HPLC) was employed to analysis the solubility of RDX in melting DNAN/MNA at the range of 87 ℃ to 95.3 ℃. The optimal chromatography conditions were as following: mobile phase is methanol/water=6/4 (V/V), and flow rate 1.0 mL·min^-1, and wavelength of detector 254 nm, and injection volume 5.0 μL. The influence of particle size, equilibration time and temperature programming on solubility was studied. Under the optimum condition, the curve of the solubility of RDX in DNAN/MNA as a function of temperature was built. Results show that the solubility of RDX increases with increasing of the temperature.

Abstract:The intermediate 1, 3-ditertiobutyl-5, 5-dinitrohexahydropyrimidine was prepared via Mannich reaction using 2, 2-dinitropropane-1, 3-diol, formaldehyde and tert-butylamine as materials, and 1, 3, 5, 5-tetranitrohexahydropyrimidine(DNNC) was obtained finally in total yield of 76% and purity of 99%. The DNNC was characterized by IR, NMR, MS spectra, elemental analyses and DSC. The results show that the decomposition temperature of DNNC is 222.2 ℃, and the friction and impact sensitivities of DNNC are 60% and 28.5 cm, respectively, showing a better thermal stability and lower mechanical sensitivity.

Abstract:The Supercritical CO₂ anti-solvent method (SAS) was used to prepare ultrafine CL-20 using Ethyl acetate as solvent and PEG-200 as surfactant. At 50 ℃, 12 MPa and mass concentration of 5%, the ultrafine CL-20 was obtained. The sample was characterized by SEM, FIRT, TGA, DSC. Result shows the surface of particles is smooth and the average particle size is 1.33 μm with good particle size distribution. And the process of CL-20 crystal formation in SAS was analyzed.

Abstract:A new dynamic calibration method as prediction-calibration-approximation used for calibration of propellants and explosives gas test by automatic gas combination system and calibration device was reported in this paper. The results indicate that the accurate measurement of multicomponent gas was achieved by dynamic calibration technology of multicomponent propellants and explosives gas. The relative standard deviation of Dynamic Calibration is less than 0.3%. As a result, the dynamic calibration technology ensures validity and unity of measuring value transfer in gas detecting.

Abstract:The structures and intermolecular interactions for octahydro-1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetrazocine (HMX)/N, N-dimethylformamide (DMF) solvate have been investigated through quantum chemistry calculations and molecular dynamics (MD) simulations. MD simulation for a β-HMX molecule immersed in DMF solvent shows that β conformation has been transformed into α form. Theoretical calculations at the MP2/6-31G^* level also indicate that the α-HMX is more stable than β-HMX in DMF solution. This explains why all HMX molecules present α-form in the polymorphic forms of HMX/DMF solvate. Geometrical optimizations at the level of MP2/6-31G^* are performed for all the possible homodimers and heterodimers between α-HMX and DMF. Results reveal that C—H…O hydrogen bond interactions exist between components. Moreover, the stabilization energy of α-HMX/DMF is very close to that of α-HMX/α-HMX and much larger than that of DMF dimer. This means that the heteromeric intermolecular forces can compete with the homomeric intermolecular forces, and co-crystallization is possible to occur from the thermodynamics viewpoint. MD simulation for the supersaturation solution of α-HMX in DMF presents the intermolecular interactions is in favor of co-crystallization. These theoretical investigations provide valuable information for understanding why there occurs co-crystallization other than re-crystallization in DMF solution of HMX.

Abstract:Theoretical calculation was used to investigate the molecular structures and orbitals of five BEBA molecules. Relative to trimethyl borate, the lowest unoccupied molecular orbital (LUMO) images of five BEBAs (1-5) molecules show that the orbitals do not appear around borate groups, and their energy levels of those unoccupied molecular orbitals around boron atom are higher. Molecular dynamics simulation was performed to investigate the interaction between title borate esters and RDX(210) as well as RDX(210) crystal faces. An obvious binding selectivity of these borate esters on RDX crystal surfaces is found. The binding energies of RDX(200)/BEBAs are higher than that of RDX(210)/BEBA(1-5). The theoretical evaluation for the binding performances of BEBA_1 and BEBA_2 with RDX are good enough, whereas the binding performances of RDX(210)/BEBA_5 and RDX(200)/BEBA_5 are contrary. It is speculated that less oxygen content of the most superficial surface of RDX(200) is benefit of forming induced effects between carbonyl of BEBA_5 and NO₂ in RDX. Such a strong combination between them offsets or even compensates the lowering of binding energy caused by depletion of nitrogen′s negative charge on amines.

Abstract:Several metallized solid rocket propellants, AP/Metal/HTPB in the ratio 68/18/14, were experimentally analyzed at the Space Propulsion Laboratory of Politecnico di Milano. Effects of the metals (micrometric and nanometric Al, B, Mg, and a variety of dual metals) on the performance of the propellant were studied and contrasted to a conventional micrometric aluminum (30 μm average grain size) taken as reference. It is shown that the propellant microstructure plays a fundamental role in controlling the critical aggregation/agglomeration phenomena occurring below and near the burning surface. Two specific effects of microstructure in terms of steady burning rate and average agglomerate size are illustrated.

Abstract:The explosion heat (Q_v), the combustion temperature(T_f) and the combustion gas generation rate(η) of boron based fuel-rich propellant contained Mg, Al and magnalium were tested to comparatively study the effects of the metal on its combustion. Results show that Mg improves Q_v, T_f, η of propellant better than Al, and the magnalium decreases the Q_v, T_f, but increases η higher than Mg. Compared with moderately boron, the coarse or fine boron increases the Q_v, T_f higher, and decrease the η lower. The explosion heat, the gas generation rate decrease and the combustion temperature increases with the increasing of the boron content.

Abstract:To decrease farther the burning rate and the flame temperature of DB propellant with low burning rate and low flame temperature, an experimental study was carried out to explore the effect of a nitro compound on the burning rate and the flame temperature. Series of DB formulations were designed with inorganic lead, organic copper salt and transition metal catalysts. The thermal decomposition and combustion of the propellants were studied by testing the burning rate and PDSC. There are three peaks of heat release on the DSC curves of DB propellant containing the energetic nitro compound, and the heat release temperatures are around 200 ℃, 280 ℃ and 350 ℃, but the third peak is not obvious. Results show that the energetic nitro compounds can effectively decrease the burning rate and the flame temperature of the DB propellant, but increase the pressure exponent, which can be improved by adding catalysts. The collaborations of the energetic nitro compounds and the catalysts can provide DB propellant lower burning rate, lower flame temperature, smaller pressure exponent, and less quantity of decomposition heat.

Abstract:The synthesis method of energetic guanidine ionic compounds with the characteristics of high enthalpy of formation, good thermal stability and environment-friendly was summarized. The effects of cation, anion, substituent group and intermolecular force on the melting point, density and energy performance of energetic guanidine ionic compounds were analyzed. The progress in the applications of energetic guanidine ionic compounds in gas generation agents, propellants and explosives was introduced and reviewed.

Abstract:The synthesis, energetic properties and development of the triazines′ energetic materials were summarized in the paper. The study on triazines′ energetic compounds can be divided into experimental studies and theoretical calculations. The structure and predicted performance of triazine compounds, based on density functional theory were collected and reviewed. The relationship between properties and structures of substituents on triazine ring was analysed, and the performance of the theoretical prediction was introduced. The prospects of the triazine-containing compounds in the field of energetic materials were looked forward with 48 references.

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