Abstract:In order to study the effect of shape and size on the molecular tailoring process of single-base propellant， three gradiently denitrated single-base propellants （seven-holes， one-hole and non-hole single-base propellants） were prepared by using hydrazine hydrate as denitration agent. Based on the Avrami model， the kinetics of the molecular tailoring process of different shapes of single-base gun propellants has been investigated. The results showed that the Avrami model could be used to describe the molecular tailoring process of three single-base propellants. The Avrami index n of seven-holes propellant was greater than 1 when the reaction temperature was in the range of 70-75 ℃， which was controlled by the chemical reaction process. When the temperature was in the range of 75-80 ℃， n<1， it was controlled by a combination of internal diffusion and chemical reaction. The Avrami index n<1 for one-hole and non-hole single-base propellants， and the molecular tailoring process was controlled by a combination of internal diffusion and chemical reaction. According to Fick"s law， the diffusion coefficient D of one-hole single-base propellants was 3.8×10^-13-10.2×10^-13 m²·s^-1， and that of non-hole single-base propellants was 3.7×10^-13~5.1×10^-13 m²·s^-1. Using the Arrhenius equation， the apparent activation energies of the seven-holes， single-hole and non-hole single-base propellants were calculated to be 45.84， 52.88 and 38.26 kJ·mol^-1， respectively. The study of the kinetics of molecular tailoring reaction for different shapes of single-base propellants can provide theoretical guidance for the controllable preparation of gradiently denitrated single-base propellants.

Abstract:A pyridine energetic molecule， N²，N⁶-dimethyl-N²，N⁴，N⁶，3，5-pentanitro-2，4，6-pyridinetriamine （NNDP）， has been synthesized in two steps from 4-amino-2，6-dichloropyridine. The process was found to be effective and simple. The structure of this compound is characterized by ¹H and ¹³C NMR， FT-IR and DSC. The crystal structure of this compound is characterized by X-ray single crystal diffraction. Results shows that compound NNDP belongs to the monoclinic space group P 2₁/c， a=16.3215（17） Å， b=7.9819（8） Å， c=13.1954（13） Å， V=1712.3（3） ų， α=90（6）^o， β=95.093（3）^o， γ=90（7）^o， Z=4. The presence of multiple nitro and nitramine groups contributes to a low decomposition temperature. Its detonation performance was predicted using EXPLO5， and sensitivity testing was conducted using the BAM standard method.It was found that the detonation performance and impact sensitivity of NNDP（D=8762 m·s^-1， p=34.5 GPa， IS=7.7 J） are comparable to those of RDX.

Abstract:To investigate the anisotropy of impact sensitivity of the cage-like energetic material hexanitrohexaazaisowurtzitane （ε-CL-20），this work used the ReaxFF-lg reactive force field and molecular dynamics method， multiscale impact loading simulations were performed on six typical crystallographic planes： （010）， （110）， （20）， （011）， （11）， and （001）. The correlation between stress， temperature， chemical reactions， and the direction of impact was analyzed. Results indicate a pronounced anisotropy in the impact sensitivity of ε-CL-20， with the sensitivity ranking of the planes as （010）>（110）>（20）≈（011）>（11）> （001）. The system exhibits the strongest thermo-mechanical and chemical responses when impacted perpendicular to the （010） plane， implying the highest sensitivity. In contrast， the weakest responses and lowest sensitivity occurs when impacted perpendicular to the （001） plane. Based on these findings， for planar layered energetic materials， impacts parallel to the molecular layers yield the highest sensitivity， while the impacts perpendicular to the molecular layer opposite result in low sensitivity.

Abstract:The content and particle size of aluminum powder in thermobaric explosives （TBXs） directly influence the energy output structure of explosions， significantly affecting the characteristic “post-combustion effect” of TBXs， which is crucial to the formation of the “thermobaric effect.” This paper discusses the influence of aluminum powder content and particle size on the explosive energy， pressure effect， thermal damage effect， and asphyxiation effect of TBXs. It also analyzes the mechanism by which aluminum influences the post-combustion reaction， identifying the optimal content and particle size range for aluminum addition in TBXs. Looking ahead， future research should focus on the reaction kinetics of energy release from aluminum powder， develop corresponding testing methods， and thoroughly analyze the energy release process of TBXs， providing a foundation for the precise control of formulation design and energy output structure.

Abstract:The initial isothermal aging behavior of poly （3-nitratomethyl-3-methyloxetane） （PNIMMO） was studied. The aging kinetic parameters and thermal aging mechanism of PNIMMO at 100-120 ℃ were investigated using an isothermal gas measuring device. The storage life of PNIMMO was determined by the Berthelot equation. The results indicate that the activation energy （E_a） is 156.42 kJ·mol^-1 and the logarithm of the pre-exponential factor （lgA） is 16.86 s^-1 when the aging depth of PNIMMO reaches 0.1%. Conversely， at an aging depth of 0.5%， E_a is measured at 156.05 kJ·mol^-1 and lgA at 16.03 s^-1， as derived from the Arrhenius equation. According to the mode matching method， the thermal aging of PNIMMO at 100-120 ℃ conforms to the mechanism function No.28， that is， the reaction order n=1/4， E_a=154.33 kJ·mol^-1. Using an aging depth of 0.1% as the evaluation criterion， PNIMMO can be stored at room temperature for 51.6 years. During the initial phase of thermal decomposition， the side chain ─O─NO₂ bond undergoes cleavage followed by hydrogenation， subsequently leading to gradual degradation of the main chain into stable polyaromatic compounds.

Abstract:For the fast and easy detection of hydrazoic acid gas， an electrosensor for in-situ detection of hydrazoic acid was prepared based on the principle of electrochemical analysis using a screen-printed electrode as a substrate and modified with carboxylated multi-walled magnetic nanotubes. The electrochemical detection of hydrazoic acid was constructed by optimizing the solvent of the modification solution， the pH value of the detection substrate， and the scanning speed The morphology and performance were characterized. The results show that the in-situ detection electrosensor for hydrazoic acid was prepared as a microelectrode with carboxylated multi-walled carbon nanotubes/glacial acetic acid modification solution， and its response current is about 121% higher than that of the unmodified electrode. The detection sensitivity is high at the substrate pH 7.5. The square root of the scanning speed is linearly related to the oxidation peak current， and the electrochemical oxidation of N₃^- is a diffusion-controlled process with good selectivity， stability， and reproducibility. The detection limit of N₃^- was 10.4 μM in the concentration range of 5×10^-5-1×10^-3 M N₃^- using the differential pulse voltammetry method. The prediction equations for the concentration of HN₃ gas produced by different NaN₃ feedstock contents at different times were derived from the online detection of the actual synthesis of HN₃ gas， and the recoveries of HN₃ are 96.8%-99.5%. In addition， the relationship between the concentration of synthesis HN₃ gas and the response current has been established.

Abstract:To understand the properties of the novel polynitrogen compound hexazine anion ［N₆］^4-， computational chemical methods were used to study the electronic structure， bonding properties and aromaticity of N₆， ［N₆］^2- and ［N₆］^4-. The M06-2X method combined with the def2-TZVP basis set was used to optimized the structures and calculated the electronic structure features， such as bond length， bond angle， dihedral angle， molecular size and so on. Subsequently， multiple bond orders were calculated， using the atoms-in-molecules （AIM） theory to calculate multiple bond properties， and drawing the electron deformation density map to directly show the bond behavior. Finally， various aromatic indices were calculated to show the aromatic characteristics of three hexazine rings. The calculation results show that by comparing with the electronic structure optimized by CCSD， the M06-2X method in the common DFT method is suitable for studying the current system. Mayer bond order shows that the N—N bond has a certain degree of σ bond characteristics. The aromaticity study shows that the［N₆］^4- is aromatic， with the aromatic harmonic oscillator model （HOMA） value at 0.96 and the nuclear independent chemical shift （NICS_ZZ（1）） at -18.97 ppm. The IR， Raman and UV-Visible spectra of ［N₆］^4- were simulated to provide reference for experimental detection.

Abstract:To investigate the influence of the structure of a laminated composite charge on its energy release during the afterburning process of aluminum powder， a composite charge with a multiple sandwich structure of uniform layer thickness was prepared by introducing two types of explosives namely high explosive and thermobaric explosive. The high explosive with a higher detonation velocity than that of the thermobaric explosive by 1.8 km·s^-1. The evolutionary process of the fire ball and the mechanical energy in different ambient environment during various reaction stages were independently investigated in free-air and confined explosion experiments. Additionally， the distribution characteristics of aluminum powder throughout the explosion were assessed through integrated numerical simulation. The results showed that the thermobaric explosive layer was axially compressed by the high explosive layer， resulting in an increase in the radial diffusion rate of both detonation products and aluminum powder. Furthermore， the average concentration of the aluminum powder cloud was reduced to 60%-80% of that in a homogeneous thermobaric charge， and even to 50% in the tail region， finally resulting in a reduction of anaerobic combustion rate of aluminum powder， as well as the mechanical energy released by aluminum powder. In the laminated composite charge， the total mechanical energy released by thermobaric explosive in detonation and anaerobic combustion process was about 81% of that in a corresponding homogeneous thermobaric charge. However， the mechanical energy produced during the aerobic combustion stage increased significantly， leading to the total mechanical energy remained approximately stable. This study indicated that the laminated composite charge structure could efficiently regulate the afterburning reaction and energy release of thermobaric explosives in different reaction stages by adjusting the spatial distribution of aluminum powder without losing the total energy of the charge.

Abstract:The cloud detonation devices typically form a fuel air mixture cloud with an approximate cylindrical shape. The morphological parameters of the cloud closely related to the charge structure strongly affect the spatiotemporal evolution law of its detonation overpressure field， which in turn has a significant impact on its detonation overpressure damage power. In order to explore the morphological effects of cloud， through the numerical calculation method for ideal detonation in cylindrical cloud， the complex dynamic process of waves during its detonation process was analyzed. The evolution and distribution law of the cloud detonation overpressure field was investigated. A similar decay law of the radial far-field peak overpressure with scaled distance was established．The dependence relationship between the detonation overpressure damage radius and the morphological parameters （ratio of radius to height） of the cloud was provided. The research results indicated that there was a significant bimodal phenomenon in the radial far-field overpressure field， due to the complex detonation process inside the cylindrical cloud. The pursuit of two peaks resulted in a characteristic mutation phenomenon of small amplitude and small range in the variation curve of the peak overpressure of detonation with scaled distance， and the larger the morphological parameter， the closer the certain position was to the detonation point．Furthermore， when the morphological parameters within the range of 2-4.5， the decay law of the detonation far-field peak overpressure with scaled distance satisfied the same similarity law. The maximum error of the overpressure damage radius obtained based on that similarity law was less than 8%. When the morphological parameters within the range of 0.5-2， the detonation overpressure damage radius decreased with the increase of morphological parameters.

Abstract:In order to guide the application of hydrogen/methane mixture as fuel， explosion experiments were carried out using a cylindrical closed vessel with an inner diameter and length of 300 mm. The effects of hydrogen fraction （X_H2） from 0 to 100% and equivalence ratio （Φ） from 0.6 to 1.4 on the flame evolution and explosion pressure were investigated. Meanwhile， CHEMKIN software was introduced to analyze the laminar burning velocity and sensitivity coefficient of the H₂-CH₄-air premixed gas. The results showed that， for a certain Φ， the maximum explosion pressure （p_max）， the maximum pressure rise rate （（dp/dt）_max）， the explosion index （K_G）， and the laminar burning velocity increased monotonically with the increase of X_H2. The duration to reach p_max and （dp/dt）_max ， named t_A and t_B， respectively， decreased gradually. After ignition， the flame surface gradually transformed from a smooth structure to a honeycomb flame lattice structure. With a constant Φ and an increasing X_H2， the duration from ignition to the termination of the explosion decreased dramatically. Meanwhile， at the same moment the flame radius increased but the fold on the flame surface increased. The simulation results showed that the elementary reactions R35 and R52 had the most significant influence on the laminar burning velocity. The maximum molar fractions of the key radicals （H， O， and OH） had a positive correlation with the laminar burning velocity， and the increase of X_H2 lead to a significant increase in the maximum molar fractions of the key radicals. The primitive reactions R38 and R84 were the dominant reactions affecting the rate of production （ROP） of key radicals.

Abstract:Nitrogen-containing compounds， acting as nitrogen donors， directly influence the types of high nitrogen compounds formed under laser irradiation. To understand the impact of various nitrogen-containing compounds on the formation of high-nitrogen compounds， three representative compounds NaN₃， Si₃N₄ and P₃N₅ were ablated using a pulsed Nd： YAG laser in a nitrogen atmosphere. The plasma characteristics and the evolution of the transient intermediates generated by laser sputtering were investigated by transient spectrometer. The findings indicate that the laser ablation of NaN₃ yields the highest number of nitrogen atoms （N Ⅰ）， monovalent nitrogen ions （N Ⅱ）， and trivalent nitrogen ions （N Ⅲ）， with the longest duration of nitrogen plasma. The lifetimes of N Ⅰ， N Ⅱ， and N Ⅲ reached 39，400 ns， 39，400 ns， and 19，450 ns， respectively. Among the three nitrogen donors， the laser ablation of NaN₃ in a nitrogen atmosphere is most likely to result in the formation of high-nitrogen or all-nitrogen compounds.

Abstract:The condensation and accumulation of Nitroglycerin （NG）-containing volatiles on various solid surfaces during the propellant rolling process， which pose safety hazards， were investigated using molecular dynamics simulation methods. The study was conducted by constructing a hybrid system model consisting of NG volatiles and solid surfaces， examining the effects of solid surface material， surface roughness， and NG content on molecular dynamics characteristic parameters such as radial distribution function， mean square displacement， diffusion coefficient， and relative density distribution of NG volatiles in the hybrid system. The findings demonstrate that as the mass fraction of NG increases， the size of volatile condensate clusters on the solid surface progressively diminishes. Conversely， the condensation ratio of volatiles exhibits a trend of initial increase followed by a decrease， with the maximum condensation ratio occurring at 70% NG， corresponding to a diffusion coefficient of 0.0364. The diffusion coefficient for the condensation of volatiles containing NG on a silica （SiO₂） surface is 2.1228， which is substantially greater than that on surfaces composed of copper （Cu）， calcium oxide （CaO）， and ferrum （Fe）. However， the uniformity of the SiO₂ surface condensate cluster is poor. The introduction of surface roughness factors has opposite effects on the condensation amount of volatiles on the SiO₂ and Fe surfaces. When the SiO₂ surface goes from smooth to roughness of 0.4 nm， the diffusion coefficient increases from 2.1228 to 10.7156， and the condensation amount of volatiles on the surface increases； however， when the Fe surface goes from smooth to roughness of 0.4 nm， the diffusion coefficient decreases from 17.5673 to 1.8462， and the condensation amount of the surface volatiles decreases.

Abstract:In order to study the effects of strain rate and tensile-shear angle on the tensile-shear strength of NEPE propellant， tensile-shear tests of the propellant for 5 tensile-shear angles （0°， 30°， 45°， 60°， 90°） and 5 strain rates （0.0012， 0.0048， 0.024， 0.12， 1 s^-1） were carried out by using tensile-shear fixtures and butterfly test specimens. The variation of tensile-shear strength with tensile-shear angle and strain rate of propellant under combined tensile-shear loading was obtained. Based on the experimental results， the tensile-shear strength limit of propellant was described by the improved circular equation， and the tensile-shear strength criterion of propellant at different strain rates was established by combining the double shear unified strength theory， and the corresponding theoretical limit surface of the unified strength of propellant was drawn. Finally， the established tensile-shear strength criterion was used to predict the tensile-shear strengths of 0.12 s^-1 and 1 s^-1 strain rates for the tensile-shear angles of 15° and 75°. The validity of the established tensile-shear strength criterion was verified by comparing the predicted results with the experimental data. The results show that the tensile-shear strength of NEPE propellant under combined tensile-shear load increases with the increase of tensile-shear angle and strain rate. By fitting and solving the material parameter values， the improved circular equation and unified strength criterion established can well describe the tensile-shear strength of NEPE propellant for different loading angles and strain rates. Based on the established strength criterion， the errors between the predicted values and the experimental values of the tensile strength limits at the strain rates of 0.12 s^-1 and 1 s^-1 for the tensile-shear angles of 15° and 75° are less than the allowable error range of the actual treatment by 15%.

Abstract:To further balance the energy and safety of 5-nitro-3-（trinitromethyl）-1H-1，2，4-triazole， four nitrogen-rich energetic ionic salts were synthesized using 2-（5-amino-1H-1，2，4-triazole-3-yl） acetic acid as a starting material through a silver salt substitution reaction. The structures of all new compounds were characterized using nuclear magnetic resonance， Fourier transform infrared spectroscopy， differential scanning calorimetry， thermogravimetric analysis， and single crystal X-ray diffraction. The results indicate that the ammonium salt， hydrazine salt， and guanidine salt of 5-nitro-3-（trinitromethyl）-1H-1，2，4-triazole exhibit higher initial decomposition temperature than that of the precursor. Moreover， the hydrazine salt and guanidine salt belong to the different crystal systems with distinct crystal packing arrangements and densities. However， they share consistent characteristics in terms of intermolecular weak interactions， with the H…O interaction being the predominant contributor. With the decreasing of the ratios of N…O and O…O interactions， the sensitivity of the nitrogen-rich energetic ionic salts to mechanical stimuli decreases. Finally， the analysis of the distribution of molecular electrostatic potential supplements the explanation for the change in impact sensitivity of 5-nitro-3-（trinitromethyl）-1H-1，2，4-triazole after salt formation. Among the four ionic compounds， the hydrazine salt exhibits outstanding detonation performance （D=8634 m·s^-1， p=30.2 GPa， I_sp=263.5 s） with relative high sensitivity. In contrast， the triaminoguanidine salt demonstrates excellent overall performance. It has a detonation velocity comparable to that of the hydrazine salt （D=8627 m·s^-1）， a heat of formation nearly 1.4 times greater than that of the precursor （ΔH_f=0.644 kJ·g^-1）， and a low mechanical sensitivity （IS=10.3 J， FS=150 N）.

Abstract:3D printing technology has the characteristics of customization， mold free， and flexibility， which can provide an effective approach for the shaping of special structure solid propellant grains in multi-thrust or multi -pulse solid rocket motors. At present， research on 3D printing of solid propellant grain has been conducted both domestically and internationally. This article focuses on the application of typical 3D printing processes such as binder jetting， photopolymerization curing， and material extrusion in the formation of heterogeneous solid propellant grains with contained complex structures， gradients， and multi material integration. It summarizes the key issues that exist in the 3D printing of these three types of solid propellant grains. The future research directions were prospected， and it was emphasized that the future manufacturing of heterogeneous solid propellant grains should focus on low sensitivity specialized solid propellant slurries， printing equipment for large grain forming， and insulation coating printing technology.

Abstract:In order to investigate the influence and regularities of planar integrated transient voltage suppressor diodes （TVS） on the performance of anti-static integrated semiconductor bridge initiator transducers， capacitor discharge firing experiments were carried out to study the effect of the parallel quantity of planar integrated TVS diodes and breakdown voltage on the electrical explosion performance. Its influence on the static electrostatic reliability performance of semiconductor bridge initiator transducers were also investigated by 500 pF/500 Ω/25 kV static discharge experiments. The results indicate that when the excitation energy approaches the upper limit of the energy absorbed per unit time by a single planar integrated TVS diode， increasing the number of parallel planar integrated TVS diodes will prolong the burst time of the SCB initiator transducer element， and may even affect the normal bursting of the SCB initiator transducer element. Conversely， if the excitation energy is insufficient to bring the energy absorbed per unit time by a single planar integrated TVS diode close to its upper limit， the bursting performance of the SCB initiator transducer element will not change with the number of parallel planar integrated TVS diodes. When the excitation voltage exceeds the breakdown voltage of the planar integrated TVS diodes， the lower the breakdown voltage of the TVS diode， the longer the burst time of the SCB initiator transducers， and the greater the burst energy， and potentially affecting the normal burst of the SCB initiator transducer element. Reducing the breakdown voltage of the planar integrated TVS diodes and increasing the number of parallel diodes can enhance the electrostatic reliability of the SCB initiator transducers. When designing an antistatic integrated semiconductor bridge chip with dimensions of 350 μm（W）×100 μm（L）×2 μm（H）， it is possible to integrate two TVS diodes with breakdown voltages slightly below 14 V， or one with a breakdown voltage slightly above 7 V.

Abstract:To develop a high-performance burning rate catalyst for solid propellant， an iron-loaded carbon nanotube material （Fe@CNTs） was synthesized by high-temperature pyrolysis of the caged precursor. The elemental composition， microscopic morphology， phase structure， specific surface area， and catalytic decomposition performance of Fe@CNTs were investigated by scanning electron microscope-energy dispersive spectrometer （SEM-EDS）， transmission electron microscopy （TEM）， X-ray diffraction （XRD）， X-ray photoelectron spectroscopy （XPS）， Fourier transform infrared spectroscopy （FTIR）， nitrogen sorption isotherm measurement （BET）， differential scanning calorimeter （DSC）， and thermogravimetry-mass spectrometry （TG-MS）. The results show that， Fe@CNTs is an iron-loaded carbon nanotube material with a high specific surface area， which can reduce the exothermic peak temperatures of octogen （HMX）， dihydroxylammonium 5，5′-bistetrazole-1，1′-diolate （TKX-50）， 1，1-diamino-2，2-dinitroethylene （FOX-7）， hexogeon （RDX）， and hexanitrohexaazaisowurtzitane （CL-20） by 1.8 ℃， 40.4 ℃， 4.9 ℃， 6 ℃， and 8.8 ℃， respectively， when the addition amount of this material is 6%. The calculations of thermal decomposition kinetics based on the Kissinger-Ozawa model show that the apparent activation energies of 6%Fe@CNTs/HMX and 6%Fe@CNTs/TKX-50 decrease by 96.9-97.1 kJ·mol^-1 and 11.2-11.9 kJ·mol^-1， respectively. Theoretical calculations of thermodynamic and thermal safety parameters indicate that HMX and TKX-50 are still in a thermodynamically stable state after adding Fe@CNTs. Based on the results of TG-MS， the possible catalytic mechanism of Fe@CNTs on HMX and TKX-50 is further proposed.

Abstract:In order to explore the propagation patterns and characteristics of methane vapor cloud combustion waves in tunnels， the CE/SE （space-time conservation element and solution element） method in LS-DYNA software was employed to establish a pre-mixed explosion model of methane and air in the tunnel， which was validated through experimental data. In this paper， typical combustion waveforms of methane vapor cloud with a concentration 9.5% in different test positions were demonstrated by numerical simulation. The propagation and evolution law of overpressure and temperature was analyzed. The injury effects of overpressure and thermal radiation on human in tunnel were investigated. It was revealed that the combustion pressure wave along the tunnel can be divided into four stages： free expansion， reflection dissipation， wall acceleration， and Mach propagation. The pressure variation presented three characteristics： wall impact rise， reflective decay， and stable propagation. The pressure wave presented a sort of periodical reflection propagation mode radially， while the intensity was declining according to the consumption of methane. The temperature field evolved symmetrically from the ignition point to the tunnel entrance and the peak temperature decayed rapidly along the path. The temperature field radiated from the ignition point to the bottom of the tunnel， leading to a gradual convergence of in a certain section and decreased slowly over time. For the injury effects caused by a combination of combustion overpressure and thermal radiation， the fatal distance was 13.51m， the severe injury distance was 13.51~23.51m， the moderate injury distance was 23.51-160 m while the concentration of methane vapor cloud was 5%. For the methane vapor cloud with a concentration 6.5%， those distances were 16.46 m， 16.46~45.36 m and 45.36~160 m respectively. As for a concentration 9.5%， the fetal distance was 20.58m and the severe injury distance was 20.58~160m.

Abstract:Herein， we develop a new method to prepare the ammonium dinitramide/pyrazine-1， 4-dioxide （ADN/PDO） cocrystal， which is highly efficient and environmental-friendly due to utilizing the reaction crystallization with pure water as the solvent， and also comprehensively characterized its performance.. The morphology and structure of the cocrystal were characterized by optical microscopy （OP）， powder X-ray diffraction （PXRD）， and single crystal X-ray diffraction （SXRD）， respectively. In detail， the ADN/PDO cocrystal was prismatic and formed by the combination of ADN and PDO molecules at a molar ratio of 2∶1. Moreover， the ADN/PDO cocrystal belongs to the monoclinic crystal system with a space group of P2₁/c， owning a theoretical density of 1.779 g·cm^-3 at room temperature. Furthermore， through the differential scanning calorimetric （DSC） measurement， it turned out that the melting point of the prepared ADN/PDO cocrystal is 113.3 ℃， which is 21.3 ℃ higher than that of ADN， and the decomposition temperature is slightly higher than that of ADN， demonstrating good thermal stability of the prepared ADN/PDO cocrystal. Then， the hygroscopicity of the prepared cocrystal， measured by the weight increment method， is significantly low at only 2.6%， while that of ADN is at 45%. In addition， calculated by the NASA CEA， the theoretical specific impulse of the cocrystal reaches 277.9 s while that of ADN is 197.5 s， demonstrating the high energy performance of the cocrystal. In conclusion， the reported method based on the reaction crystallization successfully enables the efficient production of a high-energy， low-hygroscopic ADN/PDO cocrystal， thereby facilitating the further assessment of its application performance.

Abstract:The pilot-scale energetic material wastewater is a kind of wastewater which is extremely difficult to degrade， containing high concentrations of various nitrogen-containing compounds， such as ammonia nitrogen （NH₃-N）， nitrite （NO₂^-）， nitrate （NO₃^-）， and other organic pollutants . To realize the efficient and directional removal of these nitrogen-containing compounds， boron-doped diamond （BDD） electrodes were prepared by the hot-filament chemical vapor deposition （HFCVD） method and utilized to degrade the wastewater. The effects of electrolyte composition and concentration， modified electrode type， and electrolysis device structure on the degradation efficiency were investigated. It demonstrated that adding 0.1 M sodium chloride （NaCl） electrolyte to energetic material wastewater could improve the selectivity of NH₃-N direct conversion to nitrogen （N₂）. Using Cu/BDD and Ni/BDD cathodes accelerate the conversion process of high-valent nitrogen to NH₃-N. Under the dual electrolysis cell structure system， employing Cu/BDD and Ni/BDD electrodes as anodes improve the degradation rate of NH₃-N conversion to N₂. Therefore， the approach utilizes metal-modified BDD electrodes as anodes， is expected to be a highly effective method in the rapid and selective degradation of energy material wastewater， especially when using 0.1 M NaCl as electrolyte.

Abstract:To obtain the ignition and growth model parameters of HNS-Ⅳ based polymer bonded explosive （PBX） under shock initiation， the shock wave loading method from explosive plane wave lens was used. The shock waves were attenuated by attenuators and impacted with tested explosives， and the interface particle velocity profiles between tested explosives and LiF （lithium fluoride） windows were measured by photonic Doppler velocimetry. Several explosive pellets with varying thicknesses could be mounted to the attenuator in one shot， by adjusting the thickness of attenuator to change the input pressure， the growth process of interface particle velocity was obtained. Meanwhile， the unreacted shock adiabatic curve of tested explosive was measured by the reverse-impact method， and the cylinder expansion velocity history was acquired by 10 mm diameter cylinder test. Then， the JWL （Jones-Wilkins-Lee） equation of state （EOS） parameters of unreacted explosives and detonation products were fitted with experimental results by genetic algorithm. Finally， the interface particle velocity histories between explosives with varying thicknesses and LiF windows were fitted with the ignition and growth model. The results show that the fitting correlation coefficients of EOS parameter curves for unreacted explosives and detonation products are high enough， and the obtained ignition and growth model parameters well simulate shock initiation experimental results， which can meet the requirement of initiation train design.

Abstract:In order to study the potential mechanism of unexpected ignition of confined charge in the process of penetrating multi-layer target， by integrating the designs of multi-layer nested strikers and bidirectional limited structure， a nonlinear amplification experimental method of confined charges under continuous multiple impacts loading was established. The effectiveness of the experimental method， and the intrinsic mechanism of nonlinear response amplification were analyzed. The influence of nonlinear response of charges under multiple impacts loading on ignition behaviors was studied. The results show that the experimental method can implement multiple impacts loading with sub-millisecond pulse width， and 100 MPa-scale peak stress value. When the characterized frequency of loading is close to the intrinsic frequency of confined charges， structural nonlinear response amplification emerges， and the stress amplitude increases gradually. For the same striker velocity and mass， while varying frequency of loading， the PBX-3 charges could be ignited if structural nonlinear response is amplified and could not be ignited if structural nonlinear response is not amplified. It is found that the structural nonlinear response amplification effect is an important factor leading to charge ignition.

Abstract:To investigate the combustion characteristics of ternary active metal fuels Al/B/Mg （ABM） and Al/B/MgH₂ （ABM-H）， the heat of combustion and minimum ignition energy were studied by using an oxygen bomb calorimeter and a Hartmann tube， respectively. The sub-transient process of flame propagation and the spatiotemporal distribution characteristics of temperature fields were determined by using a high-speed camera system and a high-speed infrared camera system. The results indicate that the calorific values of ABM and ABM-H are 34.1 and 32.2 MJ·kg^-1， respectively， exhibiting increases of 14.4% and 8.1% over pure Al （29.8 MJ·kg^-1）. The minimum ignition energies of ABM， ABM-H， and Al are 160-170， 100-110， and 20-30 mJ， respectively. Compared to pure Al， the combustion duration of ABM and ABM-H increase by 65.5%， 34.5% and the peak flame propagation velocities increase by 12.6%， 23.0%， respectively， at a mass concentration of 625 g·m^-3. At a mass concentration of 500 g·m^-3， ABM-H and ABM exhibit the largest peak flame propagation velocities by 45.05， 38.7 m·s^-1， and the maximum temperatures peak of flame surface by 1856， 1717 ℃， respectively， where ABM-H shows a 7.6% improvement on temperatures peak of flame surface and a faster heating-rate compared to ABM. It suggests that the ABM and ABM-H formulations significantly reduce the explosion risk of the dust/air mixture， and significantly improving the combustion performance. ABM demonstrates superior thermal effects in calorific value and duration of combustion， whereas ABM-H exhibits higher reactivity in terms of minimum ignition energy， flame propagation speed， and temperature rise rate.

Abstract:Two new explosives， C₈H₂₄N₄（ClO₄）₄ and C₈H₂₄N₄（NO₃）₄∙2H₂O， were prepared from 1，4，7，10-tetranitrocyclododecane by salt formation with nitric acid and perchloric acid respectively， which are expected to be used as emergency reserve materials of weapons in emergency wartime. The structures， thermal properties， and detonation performances of the target products were studied through single crystal X-ray diffraction， infrared spectroscopy， elemental analysis， differential thermal analysis， thermogravimetric analysis， and EXPLO 5.0 program. Results indicate that C₈H₂₄N₄（ClO₄）₄ crystallizes in the orthogonal crystal system， Pcc2 space group with a crystal density 1.968 g∙cm^-3. The crystal of C₈H₂₄N₄（NO₃）₄∙2H₂O is a dihydrate with a crystal density of 1.642 g∙cm^-3， which belongs to the monoclinic crystal system P2₁/n space group. The thermal decomposition peak temperatures of C₈H₂₄N₄（NO₃）₄∙2H₂O and C₈H₂₄N₄（ClO₄）₄ are 293.2 ℃ and 284.1 ℃， and activation energies are 131.76 kJ·mol^-1 and 195.18 kJ·mol^-1， respectively. Compounds C₈H₂₄N₄（NO₃）₄∙2H₂O and C₈H₂₄N₄（ClO₄）₄ exhibit excellent detonation properties， showing very promising performance values （C₈H₂₄N₄（NO₃）₄∙2H₂O， D=8058 m∙s^-1， p=24.0 GPa； C₈H₂₄N₄（ClO₄）₄， D=8680 m∙s^-1， p=36.2 GPa）. Moreover， the impact sensitivities of C₈H₂₄N₄（NO₃）₄∙2H₂O and C₈H₂₄N₄（ClO₄）₄ are 36 J and 33 J， respectively， and their friction sensitivities are higher than 360 N.

Abstract:Fluoropolymers such as polyvinylidene fluoride （PVDF） can effectively inhibit the agglomeration of aluminum powder and enhance its reactivity. However， the affinity between fluorinated polymers and the surface of Al particles covered by alumina is poor， and the inhibitory effect of fluorinated polymers directly coating the Al surface on Al aggregation is not ideal. In this study， a microwave-enhanced reaction method was used to obtain hydroxylated modified PVDF-OH. PVDF-OH was coated on the surface of aluminum powder by solvent/non-solvent method for preparation Al@PVDF-OH. Subsequently， the prepared Al@PVDF-OH composite fuel is used to prepare composite solid propellants. The molecular structure and elemental composition of PVDF-OH were studied using infrared spectroscopy and X-ray diffraction. Using equipment such as scanning electron microscope， differential scanning calorimeter， high-speed camera， and oxygen bomb calorimeter study the microstructure composition and combustion performance of Al@PVDF-OH composite fuels. The results showed that the PVDF-OH prepared by microwave-assisted preparation had a higher hydroxyl content， and the optimal treatment condition was 1 minute at a microwave power of 240 W. The combustion performance of Al@PVDF-OH composite fuel was superior to that of Al@PVDF composite fuel coated with unmodified PVDF and Al@PVDF-OH（H） composite fuel coated with heat-modified PVDF-OH（H）. The optimal PVDF-OH content was found to be 15%. Compared to pure aluminum， the combustion heat value of Al@PVDF-OH composite fuel with 15% PVDF-OH increased from 19140 kJ·kg^-1 to 24912 kJ·kg^-1. Combustion tests mixed with ammonium perchlorate （AP） showed that the ignition delay time of Al@PVDF-OH composite fuel shortened from 77 ms to 70 ms， and the burning rate increased from 195.7 mm·s^-1 to 225.7 mm·s^-1 compared to pure aluminum. Compared to aluminum-based solid propellants， solid propellants based on Al@PVDF-OH composite fuel exhibited an increase in combustion heat value from 13281 kJ·kg^-1 to 14020 kJ·kg^-1， an increase in burning rate from 1.281 mm·s^-1 to 1.915 mm·s^-1， and a reduction in the particle size D₉₀ of condensed phase combustion products from 74.324 μm to 52.749 μm.

Abstract:To gain a comprehensive understanding of the properties changes of TNT crystals under strong magnetic field radiation， the morphological changes， the lattice constants and the thermal decomposition characteristic were explored using the scanning electron microscope， X-ray diffraction， Raman spectroscopy and differential scanning calorimeter （DSC）， respectively. Moreover， the variations of lattice constants， molecules distributions， mechanical properties and theoretical impact sensitivity of TNT under magnetic field radiation were investigated by molecular dynamics simulations. The experimental results， with the application of 6 T magnetic field， showed that the microscopic morphology was changed from the scale-needle structure to the irregular block structure， and the exothermic peak temperature of thermal decomposition was increased from 289.6 ℃ to 304.1 ℃. However， the crystal phase structure and lattice constants of the TNT remained unchanged. Furthermore， theoretical investigations indicated that the TNT lattice constant not affected by magnetic field radiation， but the magnetic field did change the molecules distribution in the TNT crystal. The 8 T magnetic field radiation significantly improved the ductility of TNT. However， it simultaneously increased the impact sensitivity of TNT by comparing the ratio for the longest trigger bonds.

Abstract:The planetary motion of impeller in the vertical mixer can effectively promote the dispersed circulation and homogeneous distribution of different material components， which has been employed in the preparation procedure of solid propellant slurry. However， the mixer involves complex interfaces and motions that it is difficult to study the mixing mechanism and rheological property of slurries by traditional methods. Based on the smoothed particle hydrodynamics （SPH）， the continuum was discretized into the conserved particles with physical quantities for simulating the interaction between the propellant slurry and blades under laminar flow. A meshless method for the mixing process of propellant slurries in non-Newtonian fluid state was developed by combining the Herschel-Bulkley （HB） constitutive model. The numerical simulations were compared with the experiments to verify the accuracy of the proposed model. The correlations of the blade motion parameters and power consumption were explored. The effects of geometric configurations and rotation modes on the mixing uniformity of slurries and the torque loads of impellers were analyzed. Research findings indicate that the simulation and literature experiment results have a good agreement that the average relative error between them is around 4.98% in the non-Newtonian fluid with shear rate index n=0.47. The mixing uniformity index of planetary impellers increased by 8.9% and 7.3% respectively than those of central and eccentric impellers after stirring for 2.65 s. The maximum amplification in torque can reach 38.4% within the revolution radius range of 0.11D_w-0.23D_w at Reynolds number Re=1.

Abstract:As an important thermodynamic parameter of explosives， thermal conductivity significantly affects the ignition response characteristics of explosive charge. In order to quickly and effectively obtain the thermal conductivity of explosives without tests， an axisymmetric heat conduction theoretical model of typical cylindrical charge structure is established， and its steady-state analytical solution is derived. Also， a method for calculating the thermal conductivity of explosives is proposed based on the slow cook-off experimental data. The thermal conductivity of a new type of insensitive explosive， GOL-1（HMX/Al/AP/Binder）， is determined. The numerical simulation results of the ignition response of small-size charge structure under typical cook-off conditions shows that the calculated results of the charge center temperature-time curves at different heating rates are basically consistent with the experimental results， and the deviations of ignition temperature at charge center and ignition time between the calculated and experimental results are 2.27% and 1.12% at most， which indicates the effectiveness of the thermal conductivity of the GOL-1 and the feasibility of the numerical simulation method. The established calculation method reveals the thermal conductivity characteristics and rules based on the temperature-time curves of slow cook-off experiments， which is more suitable for calculating the thermal conductivity of explosives compared with volume-weighted method and string or parallel heat conduction model. In the absence of experimental data for determining the thermal conductivity of new explosives， this method is an effective determination method， providing a basic parameter for the design and evaluation of thermal safety of ammunition and promoting the development of digital design and quantitative evaluation of safe ammunition.

Abstract:To investigate the cook-off response characteristics of JEO explosive （NTO/HMX/additives）， an experimental system for multi-point temperature and pressure measurements during the cook-off process of explosive was devised. The cook-off experiments of JEO explosive were conducted at two different heating rates of 5 ℃·min^-1 and 2 ℃·min^-1 to obtain the ignition time， ignition temperature， temperature history at different positions within the explosive， and pressure evolution inside the device. The effect of heating rates on temperature and pressure variations and reaction intensity during the cook-off process of JEO explosive was analyzed. Furthermore， based on the experimental research， a multiphase flow species transport model for explosive cook-off was adopted considering the influence of pressures on the thermal decomposition reaction of explosive， and numerical simulations were conducted to investigate the thermal decomposition process of JEO explosive under different heating rates using Fluent software. The results indicate that the thermal decomposition reaction of JEO explosive proceeds slowly before phase transition， while it accelerates significantly afterwards， leading to a rapid increase in temperature and an exponential growth in pressure until ignition. The ignition temperature of JEO explosive is approximately 220 ℃， and its response level is deflagration under the constraint conditions of this experiment， demonstrating excellent thermal safety. As the heating rate decreases， the ignition time of JEO explosive prolongs， and the ignition location shifts from the edge of the charge towards the center， resulting in an increased intensity of the reaction. During the thermal decomposition process before ignition， only a small portion of the explosive undergoes reaction， with the majority of the reaction occurring during the combustion stage after ignition.

Abstract:To improve the ignition reliability of firearm firing-ignition systems， the Lagrangian-Eulerian fluid-structure coupling method （ALE） was used to establish the ignition model of the firing-ignition systems， and a parametric simulation platform was built. The pressure start time was used as the ignition output performance characteristic parameter to establish the ignition reliability proxy model of the firearm firing-ignition system. The reliability of the firing-ignition systems under the influence of changes in structure and assembly parameters was simulated and studied. At the same time， based on small-caliber rifle firing-ignition system， an ignition system simulation test device was designed， and experimental research on the ignition performance and reliability of the ignition system was carried out to verify the ignition model. The results show that the error between the calculation results of the firearm firing-ignition reliability analysis model and the experimental results is 0.72%， indicating that the model has good accuracy. The influence rule of the average change of each factor on the system reliability is as follows： striking pin protrusion> locking gap> fire table head diameter> primer shell thickness> primer loading depth> firing pin head diameter. The standard deviation change has little impact on system reliability. This study provides theoretical and technical guidance for the reliability design of firearm firing-ignition systems.

Abstract:The morphology and structure of energetic materials have significant impact on their various properties. In order to improve the inherent performance of existing energetic materials and meet the different application requirements of weapon， the assembly of energetic materials is an effective technology. Based on the relevant works of domestic and foreign scholars， the current methods of energetic materials assembly and the effects on performances were summarized from two perspectives： the directly affecting the structure of single-component energetic materials through assembly and regulating their performance， and the assembly components and composite structure of multi-component composite energetic materials synergistically regulating the performance. The enlightenment of other functional materials assembly for energetic material was elaborated. Currently， the assembly of single-component energetic materials can achieve new crystal morphology， while multi-component assembly can compensate for the inadequacy of available performance control， and achieve synergistic improvement of energy and safety performance. However， the development of energetic material assembly still faces problems such as monotonous assembly methods， difficult process control， unclear assembly mechanisms， and insufficient research on multi-components. Future research may focus on three perspectives： the improvement of crystal assembly theory for energetic materials， the development of mesoscopic characterization techniques， and the exploration of new assembly technologies.

Abstract:The solidification process of melt-cast explosive is a significant step during its research and manufacture. Solidification， and related charge quality play key roles in the detonation performance and safety of explosives. Based on domestic and foreign research works， the development of solidification techniques of the melt-cast explosive is systematically summarized from three aspects： finite element simulation， solidification process and on-line detection methods. The application of the finite element simulation in flow -temperature-stress field simulation during casting and solidification process of the melt-cast explosive is reviewed. The formation of defects during the solidification process and the effects of different techniques on solidification are elucidated. Furthermore， the application of on-line detection of temperature， stress-strain， viscosity， and internal structure in the high-quality precision forming techniques of melt-cast explosive is discussed. The development of numerical simulation， solidification process optimization and on-line detection technique in melt-cast explosive can provide vital theoretical and technical guidance for the design and development of the solidification equipments and the quality improvement of solidified charges. In the future， the improvement of the charge and solidification technique requires further development and application in aspects such as model construction of equipment-material， safety of process equipment， precise control of process conditions， real-time information monitoring， on-line detection and adaptive regulation.

Abstract:Energetic materials serve as the energy source for munition damage， directly impacting the strike range and effectiveness of munitions. With the increasing strategic requirements of modern weapon systems for high energy， high efficiency and high security， research on the thermal properties of energetic materials has gained more attention. The thermal properties of energetic materials not only directly affect the energy output， control and regulation of energetic materials， but also are related to the safe transportation， storage and use. In order to provide a reference for the research methods of thermal properties of energetic materials， this paper systematically reviews the thermal performance characterization techniques and theoretical prediction models applied to energetic materials in recent years， involving the analysis of thermal decomposition reaction mechanism， combustion performance test， detonation performance evaluation and safety performance prediction， and analyzes and compares the characteristics and application scope of each characterization technology. Finally， it proposes that the experimental characterization technology in future research should be developed in the direction of high integration， high spatiotemporal resolution， small dose non-contact interference， and real-time monitoring and analysis. In the computational simulation research， it is necessary to co-construction and share the standard database according to the actual production of energetic materials， in order to obtain a high-precision and high-efficiency performance prediction model.