• Review on Advanced Analytical Characterization Techniques for the Chemistry of Energetic Materials

  YING zi-jian, CHEN jian-bo, XU jin-jiang, YU qian, HE xuan, ZHU chun-hua, HUANG shi-liang, YANG xi, LI shi-chun

  Online:December 19, 2024  DOI: 10.11943/CJEM2024097

  Abstract(8) HTML(152) PDF(11.69 M)( 32)

  Abstract:Analytical characterization techniques are indispensable tools for scientific research and production in the chemistry field of energetic materials. Analytical characterization techniques for energetic materials mainly includes chromatography， mass spectrometry， wave spectrum， spectroscopy， thermal analysis， microscopy， scattering and diffraction， etc. Through the qualitative/quantitative analysis of characterization technology， the chemical structure， component content， microscopic morphology and other information of energetic materials can be obtained， thereby providing important data results for energetic materials in synthesis characterization， quality control， inventory maintenance， public safety， environmental monitoring and other scenarios， which greatly promotes the development of energetic materials. In recent years， analytical characterization techniques have exhibited obvious multidisciplinary cross-integration characteristics on the basis of traditional analysis metheds， and have gradually developed in the direction of automation， intelligence， in-situ online， multi-scale penetration， high temporal and spatial resolution. In order to understand the current status and trends of analytical characterization techniques for energetic materials well， this paper systematically reviews the technical connotation， functional characteristics and application status of each major analytical method， and discusses future development trends to provide support for related analytical characterization research in the field of energetic materials .

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• Optimization of the Preparation Process of Nitro Gradiently Distributed Single-hole Propellant Based on Response Surface Methodology

  FAN Hong-lei, GU Yu-le, PENG Zhi-hua, WANG Xin-yu, LI Shi-ying, LI Chun-zhi, WU Xiao-qing, XIAO Zhong-liang

  Online:December 19, 2024  DOI: 10.11943/CJEM2024196

  Abstract(5) HTML(54) PDF(1.54 M)( 14)

  Abstract:The response surface methodology （RSM） along with Box-Behnken design was firstly applied to optimize the denitration process of the single-hole propellant. The effects of three main influencing factors， hydrazine hydrate concentration， reaction temperature and reaction time on the denitration rate in the denitration process of single-hole propellant were investigated. A quadratic mathematical model with the denitration rate as the response value was established. The results showed that the degree of influence of each factor on denitration rate was hydrazine hydrate concentration > reaction time > reaction temperature， and the interaction between the factors was not significant. The correlation coefficient of the established quadratic model is 0.9774. The experimental values of denitration rate and the predicted values of the model were in good agreement when multiple experiments were conducted within the range of the factor levels， indicating that the proposed quadratic model is highly reliable and can be used to predict the denitration rate in the denitration process of the propellant and optimize the process conditions. Through the characterization of the structure and combustion performance of the single-hole propellant before and after denitration， it is further confirmed that the gradient nitrate single-hole propellant have a gradient distribution of nitrate group concentration in the surface layer and at the edge of the hole， with excellent progressive burning performance.

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• Interior Ballistic Performance Prediction of Desensitized High-Energy Nitramine Gun Propellants

  GUO Zhi-gang, LI ZI-chao, LI Man-man, WU Rui, WEI Lun, YU Hui-fang, WANG Qiong-lin, WEN Xiao-mu

  Online:December 19, 2024  DOI: 10.11943/CJEM2024280

  Abstract(2) HTML(60) PDF(1.33 M)( 17)

  Abstract:To obtain the factors which affect the interior ballistic performance of desensitized high-energy nitramine gun propellants， the interior ballistic model was built through the closed vessel test and the 14.5 mm ballistic test. The correction coefficients were fitted by the particle swarm optimization algorithm. Then， the effects of muzzle velocity V₀ and maximum chamber pressure p_m by burning progressive factor Pr and charge mass ω were calculated and analyzed through the model theory. It was found that， the correction coefficient of burning rate χ and the utilization coefficient of propellant force η should be considered to predict the dynamic combustion characteristics of high-energy nitramine gun propellants by the classical interior ballistic theory. Compared with the case of static combustion， the relative increase of burning rate could exceed 10% in the dynamic combustion. Meanwhile， because of the energy dissipation， only about 80% of the propellant force can be effectively converted into the kinetic energy of projectile in the theoretical calculation. In result， the interior ballistic performance of gun propellants is affected by the coupling of Pr， ω， χ and η. As the major mechanism， the interior ballistic performance is significantly affected by the static combustion characteristics and the charge mass. There is a linear positive correlation between V₀ and ω， while p_m can be expressed by an exponential function of ω， and the coefficients in different correlations are determined by Pr. Nevertheless， with the different process conditions， the fluctuations of χ and η lead to the varying of interior ballistic performance， which increases the prediction deviation of the fitting correlation.

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• Synthesis and Properties of 6-Amino-4-（trinitromethyl）-2-carbonyl-1H-1，3，5-triazine

  ZHANG Tong-wei, XU Yuan-gang, LU Ming

  Online:December 12, 2024  DOI: 10.11943/CJEM2024239

  Abstract(36) HTML(88) PDF(1.41 M)( 71)

  Abstract:A novel high-energy compound， 6-Amino-4-（trinitromethyl）-2-carbonyl-1H-1，3，5-triazine， was synthesized in one step. The crystal structure of this compound was characterized by X-ray single crystal diffraction. Its structure and properties were characterized by ¹H and ¹³C NMR， FT-IR and DSC. The detonation performance was calculated by EXPLO5. The sensitivity testing was performed according to the BAM standard method.The compound crystallizes in orthorhombic space group C 2/c， a=10.183（4） ?， b=9.388（3） ?， c=21.324（8） ?， V=2005.9（13） ?³， α=90°， β=100.246（10）°， γ=90°， Z=8. The calculated detonation velocity and pressure for compound 1 are 8167 m·s^-1 and 27.6 GPa， respectively， with measured impact sensitivity of 6 J and friction sensitivity of 210 N.

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• Preparation and Properties of TKX-50/AP Composite Microspheres

  WANG Xin-fei, YANG Jun-qing, ZHAO Han-xiao, WANG Ting-hui, HAO Ga-zi, XIAO Lei, JIANG Wei

  Online:December 10, 2024  DOI: 10.11943/CJEM2024267

  Abstract(27) HTML(172) PDF(2.03 M)( 72)

  Abstract:To obtain new energetic materials with high energy， low sensitivity and liable storage， TKX-50/AP composite microspheres were prepared by spray drying method. The effects of different feed rates on the morphology of composite microspheres were investigated， and the optimum process conditions were obtained. The morphology and crystal form of the samples were characterized by scanning electron microscope， X-ray diffractometer and Fourier infrared spectrometer. The thermal decomposition performance， impact sensitivity and hygroscopicity of the microspheres were also studied. Results show that the samples are spherical particles with sphericity of Φ=96.40% and d₅₀=1.33 μm at the feed rate of 3.6 mL·min^-1. The crystal structure is different from that of mechanical mixing of TKX-50 and AP. The thermal decomposition activation energy is 184.43 kJ·mol^-1， the characteristic drop is 50.1 cm， and the hygroscopicity is 37% lower than that of the physical mixing， showing excellent safety performance.

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• Cook-off Response Process of GAP-based Solid Propellants Under Nozzle Structural Constraints

  YANG Jun-sen, JIN Feng-kai, JI Kang-yu, WU Hai-bo, WU Yi

  Online:December 10, 2024  DOI: 10.11943/CJEM2024191

  Abstract(11) HTML(62) PDF(2.70 M)( 41)

  Abstract:The nozzle structural constraints of solid rocket motors significantly affect the response process of propellants under cook-off stimuli. To study the influence of nozzle throat diameter on the cook-off response of GAP-based solid propellants， a thermal load loading and control system for nozzle structural test pieces was designed and constructed. Using high-speed laser schlieren imaging technology， the entire cook-off response process of GAP-based propellants under the constraints of motor nozzle structures was observed. Additionally， the temperature of test pieces and the shock wave overpressure generated upon the ignition response were measured. The results indicate that the cook-off response of GAP-based solid propellant specimens with nozzle constraints can be divided into the following stages： softening and expansion of the propellant before ignition， and flame acceleration， deflagration-to-detonation transition （DDT）， casing failure， and deflagration process after ignition. The post-ignition response lasts only 0.5-2 milliseconds. From the pressure curve， it is evident that during the flame acceleration phase， the pressure grows slowly. When the nozzle throat diameter is relatively small， flow choking is more likely to occur. Once choking occurs， pressure and burning rate rapidly increase and reinforce each other， ultimately leading to deflagration-to-detonation transition. In contrast， for test pieces with large nozzle throat diameters， the rapid pressure rise cannot occur or be sustained， reducing the likelihood of deflagration-to-detonation transition and maintaining the structural integrity of test pieces.

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• Preparation and Properties of Modified Spherical ADN Materials with Amine Compounds

  QU Wei-chen, YAN Jia-wei, XIA Wen-tao, LI Lei, DU Fang, WU Peng, LIN Yu-hui, HE Jian-ming, TAO Bo-wen

  Online:December 10, 2024  DOI: 10.11943/CJEM2024222

  Abstract(4) HTML(140) PDF(3.51 M)( 38)

  Abstract:Ammonium dinitramide （ADN）， as a high-energy green oxidizer， faces significant challenges in engineering applications within solid propellants due to its high surface polarity and strong hygroscopicity. To improve the hygroscopicity of ADN， both emulsion and liquid-phase methods were employed to graft hydrophobic amine compounds， oleylamine and 4-fluorobenzylamine， onto the surface of spherical ADN （PADN）， thereby preparing the modified spherical ADN materials （PMADN）. The structure and properties of the modified ADN materials were characterized using scanning electron microscopy-energy dispersive spectroscopy （SEM-EDS）， thermogravimetric-differential thermal analysis （TG-DTA）， and X-ray photoelectron spectroscopy （XPS）. Additionally， hygroscopicity studies were conducted using the desiccator equilibrium method. The results confirmed both amine compounds were grafted successfully and the spherical morphology of the modified ADN materials was intact. The thermal decomposition temperature of the modified ADN materials increased from 196.3 ℃ （raw ADN） to 198.3 ℃ and 200.7 ℃， and the impact sensitivity improved from 17.95 J to 24.35 J and 28.8 J， respectively. After 144 h under 25 ℃ and 57% relative humidity， the moisture rates of the two modified spherical ADN materials were 1.37% and 1.07%， decreasing 74.95% and 80.44% compared to that of the raw ADN. Additionally， no caking or liquid water was observed on the surface， indicating the modified ADN materials had excellent anti-hygroscopic properties.

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• Thermal Behavior and Decomposition Mechanism of 2，2-Azobi［4，5-bis （tetrazole-5-yl）］-1，2，3-triazole

  LIU Shu-liang, CAI Tao, ZHANG Li-nan, QI Yuan, MA Hui-chao, LIN Qiu-han

  Online:November 27, 2024  DOI: 10.11943/CJEM2024229

  Abstract(69) HTML(156) PDF(1.93 M)( 143)

  Abstract:To study the thermal decomposition behavior of 2，2-azobi［4，5-bis（tetrazole-5-yl）］-1，2，3-triazole （NL24）， the structure， morphology and thermal decomposition characteristics of NL24 were studied by means of scanning electron microscopy， thermogravimetric analyzer， differential scanning calorimeter and thermogravimetric infrared mass spectrometry. The kinetic parameters such as apparent activation energy and pre-exponential factor were calculated by Kissinger， Ozawa and ?atava-?esták method， and the thermal decomposition mechanism of NL24 was speculated. Results show that NL24 has two main weight loss stages at the heating rate of 10 ℃·min-1 . The first weight loss stage occurs at about 180 ℃， which belongs to the volatile endothermal process of dimethyl sulfoxide. The violent thermal decomposition of NL24 occurs at the second weight loss stage between 270 ℃ and 300 ℃， which has not only rapid gas generation rate， but also belongs to autocatalytic reaction. The main gaseous products are N2， HCN， HN3， etc. The apparent activation energy and pre-exponential factor of the decomposition process are 174.69 kJ·mol-1 and 1016.60 s-1 ， respectively. The reaction model of thermal decomposition stage of NL24 is random nucleation and subsequent growth.

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• Influence of Single-base Propellant Type on the Kinetics of Molecular Clipping Reaction Process

  PENG Zhi-hua, WANG Xin-yu, GU Yu-le, FAN Hong-lei, LI Shi-ying, LI Chun-zhi, WANG Xiao-qian, XIAO Zhong-liang, WU Xiao-qing

  Online:November 21, 2024  DOI: 10.11943/CJEM2024183

  Abstract(44) HTML(100) PDF(2.40 M)( 158)

  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.

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• Synthesis and Properties of N²，N⁶-Dimethyl-N²，N⁴，N⁶，3，5-Pentanitro-2，4，6-Pyridinetriamine

  ZHANG Rong-zheng, LU Ming, XU Yuan-gang

  Online:November 21, 2024  DOI: 10.11943/CJEM2024211

  Abstract(59) HTML(112) PDF(1.56 M)( 183)

  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） ?， b=7.9819（8） ?， c=13.1954（13） ?， V=1712.3（3） ?³， 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.

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• Simulation Study on the Anisotropy Rule of Impact Sensitivity of ε-CL-20

  LIANG Lin, WANG Ya-jun, GAN Qiang, ZHANG Wen-bo, REN Shu, LI Gen, FENG Chang-gen

  Online:November 19, 2024  DOI: 10.11943/CJEM2024121

  Abstract(36) HTML(26) PDF(4.70 M)( 163)

  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.

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• Initial Thermal Aging Behavior of PNIMMO Studied by Isothermal Gasometric Method

  GONG Xue-ling, GUAN Jian, LIU Hong-ni, MO Hong-chang, ZHANG Qing-yuan, PENG Ru-fang, JIN Bo

  Online:November 19, 2024  DOI: 10.11943/CJEM2024157

  Abstract(46) HTML(72) PDF(1.25 M)( 235)

  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.

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• Detection of Hydrazoic Acid Gas by Carboxylated Multi-walled Carbon Nanotube Modified Screen Printed Electrode

  LIN Jun-chi, BA Shu-hong, HAN Ji-min, YANG Li

  Online:November 15, 2024  DOI: 10.11943/CJEM2024257

  Abstract(24) HTML(46) PDF(1.78 M)( 136)

  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.

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• Experimental Study and Numerical Simulation of Mesoscale Dewetting Behavior of HTPB Tripropellant under Different Temperature Conditions

  ZOU Zi-jie, QIANG Hong-fu, WANG Zhe-jun, LI Shi-qi, WANG Xue-ren, LI Yi-yi

  Online:November 14, 2024  DOI: 10.11943/CJEM2024208

  Abstract(29) HTML(154) PDF(5.46 M)( 149)

  Abstract:This study conducted micro-CT characterization experiments on HTPB propellant under wide temperature range and uniaxial tension conditions. The mesoscopic dewetting damage behavior of the propellant with three environmental temperatures of -20 ℃， 20 ℃， and 50 ℃ was analyzed， and a three-dimensional mesoscopic representative volume element model based on the volume proportions of the mesoscopic components of HTPB propellant was constructed. The stress-strain relationship and dewetting proportion-strain relationship of the model for different temperatures and strain rates were analyzed. It was found that HTPB propellant had more severe dewetting at low temperatures （-20 ℃）， with an interface dewetting proportion of nearly 30% when the propellant fractured， resulting in a pronounced stress softening phenomenon of the propellant. Through numerical simulation， it was found that the propellant undergoes more severe dewetting with low temperature and high strain rate， which greatly deteriorates the mechanical properties of the propellant. By comparing experimental and simulation results， the numerical model constructed in this paper can effectively predict the dewetting damage behavior and macroscopic mechanical properties of propellants.

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• Theoretical Study of the Electronic Structure， Bonding properties and Aromaticity of Hexazine Anion ［N₆］^4-

  JIANG Shuai-jie, ZHANG Guang-yuan, XU Yuan-gang, WANG Peng-cheng, LU Ming

  Online:November 13, 2024  DOI: 10.11943/CJEM2024205

  Abstract(33) HTML(122) PDF(1.86 M)( 150)

  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.

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• Experimental and Numerical sdudy on the Explosion Characteristics of Hydrogen-Methane-Air in a Closed Vessel

  MEI Liang, GUO Jin, HUANG Shi-kai, WANG Jin-gui

  Online:October 25, 2024  DOI: 10.11943/CJEM2024186

  Abstract(29) HTML(86) PDF(3.42 M)( 175)

  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.

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• Plasma Characteristics of Typical Nitrogen-containing Compounds in Nitrogen Atmosphere

  LIU Hai-qing, XIANG Shu-jie, FANG Pu-yixing, LI Chun-tian, SHEN Rui-qi, ZHANG Wei

  Online:October 15, 2024  DOI: 10.11943/CJEM2024101

  Abstract(51) HTML(88) PDF(3.47 M)( 232)

  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.

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• Molecular Dynamics Simulations of the Condensation Behavior of Nitroglycerine-containing Volatiles on Solid Surfaces

  HUANG Chao-ran, PAN Bao, LI Guo, WANG Yu, XIE Lin-sheng, LIU Suo-en, ZHAO Jun-bo, LIU Yun-zhang, TAN Kai-xin

  Online:September 26, 2024  DOI: 10.11943/CJEM2024178

  Abstract(57) HTML(148) PDF(2.50 M)( 252)

  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.

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• A Strength Criterion of NEPE Propellant Based on Tensile-shear Load Tests

  LIU Fan, QIANG Hong-fu, WANG Jia-xiang, WANG Zhe-Jun, WANG Xue-ren

  Online:September 19, 2024  DOI: 10.11943/CJEM2024193

  Abstract(99) HTML(68) PDF(1.65 M)( 530)

  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%.

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• Synthesis and Performance of 5-Nitro-3-（trinitromethyl）-1H-1，2，4- triazole Nitrogen-Rich Energetic Ionic Salts

  WANG Xian-feng, YANG Feng, XU Yuan-gang, LU Ming

  Online:September 18, 2024  DOI: 10.11943/CJEM2024224

  Abstract(109) HTML(64) PDF(2.31 M)( 387)

  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）.

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• 3D Printing Technology in the Manufacturing of Solid Propellant Grain： A review of Applications and Prospects

  SONG Shi-xiong, REN Quan-bin, WANG Jia-wei, PANG Ai-min, TANG Min

  Online:September 14, 2024  DOI: 10.11943/CJEM2024129

  Abstract(169) HTML(262) PDF(2.95 M)( 669)

  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.

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• Impact Factors of Planar Integrated TVS diodes on the Performance of Semiconductor Bridge Initiator Transducers

  TAO Yu-ren, WANG Lei, ZHOU Bin, WANG Jun

  Online:August 26, 2024  DOI: 10.11943/CJEM2024112

  Abstract(133) HTML(174) PDF(1.69 M)( 1029)

  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.

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• Research on Combustion Characteristics and Injury Effects of Methane Vapor Clouds in Tunnels

  GU Lin-lin, XU Yong-hang, ZHU Huang-hao, WANG Zhen

  Online:August 20, 2024  DOI: 10.11943/CJEM2024155

  Abstract(146) HTML(98) PDF(2.45 M)( 1082)

  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.

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• Using BDD Electrode for Electrochemical Treatment of Nitrogen in Real Energetic Material Wastewater

  YOU Jia-jun, WANG Bing, XIONG Ying, WANG Jian

  Online:June 04, 2024  DOI: 10.11943/CJEM2024092

  Abstract(314) HTML(108) PDF(2.05 M)( 1567)

  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.

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• Parameters of the Ignition and Growth Model for HNS-Ⅳ based PBX under Shock Initiation

  ZHAO Ya-qi, YANG Sha, CAO Wei, GUO Wei, SONG Qing-guan, DUAN Ying-liang, HUANG Bing, HAN Yong

  Online:May 15, 2024  DOI: 10.11943/CJEM2024052

  Abstract(408) HTML(256) PDF(1.19 M)( 1386)

  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.

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• Combustion Characteristics of Ternary Reactive Metal Fuels Al/B/Mg and Al/B/MgH₂

  CHENG Zhi-peng, XIA Yu, LUO Yi-min, MA Teng, XU Fei-yang, ZHANG Yu, WU Xing-liang, XU Sen

  Online:August 16, 2024  DOI: 10.11943/CJEM2024100

  Abstract(241) HTML(252) PDF( 1175)

  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.

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Vol, 32, No.12, 2024     Energetic Materials for Vapor Cloud/thermobaric Explosion

>Editorial

• introduction to special subject

  HAN Zhi-wei

  2024,32(12):1256-1256, DOI:

  Abstract(0) HTML(1) PDF(1.16 M)( 1)

  Abstract:无

>Perspective

• Analysis on Development Tendency of Fuel Air Explosive

  WANG Bo-liang

  2024,32(12):1257-1259, DOI: 10.11943/CJEM2024214

  Abstract(0) HTML(0) PDF(837.55 K)( 1)

  Abstract:

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>Safety Performance and Assess

• Characteristics of Spatial Distribution of Aluminum Powder and Afterburning Energy Release During the Explosion Process of Laminated Composite Charge

  SHEN Fei, WANG Yuan-jing, Wang Yi-xin, WANG Xuan-jun

  2024,32(12):1260-1269, DOI: 10.11943/CJEM2024221

  Abstract(0) HTML(2) PDF(2.24 M)( 0)

  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.

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• Influence of Cloud Morphology on Cloud Detonation Overpressure Damage Power

  WANG Xi-meng, XUE Kun

  2024,32(12):1270-1279, DOI: 10.11943/CJEM2024202

  Abstract(0) HTML(1) PDF(2.19 M)( 0)

  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.

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• Safety and Energy Level of RDX/Al/AP/ADN Thermobaric Explosives

  LEI Kang, ZHANG Jian-xin, FANG Ming-kun, XU Fei-yang, JIANG Xi-bo, WU Xing-liang, XU Sen

  2024,32(12):1280-1286, DOI: 10.11943/CJEM2024189

  Abstract(0) HTML(0) PDF(964.77 K)( 0)

  Abstract:In order to explore the application prospects of a new high-energy oxidizer ammonium dinitramide （ADN） in thermobaric explosives， ammonium perchlorate （AP） was replaced by ADN to prepare five formulations of thermobaric explosives with different ADN/AP mass ratios （AP， ADN∶AP=1∶3， 1∶1， 3∶1， ADN）. The mechanical sensitivity and thermal stability of the formulations were tested by impact sensitivity instrument， friction sensitivity instrument and differential scanning calorimetry （DSC）. The energy level of five different formulations was calculated by Explo5 software， meanwhile relevant energy parameters were measured by combustion calorimeter and detonation calorimeter. The results indicated that the characteristic drop height of impact sensitivity and the explosion probability of friction sensitivity of the fomulation using pure AP as oxidizer were 17.9 cm and 12%， respectively. But as soon as AP was replaced by ADN in various mass fraction， the characteristic drop height of impact sensitivity and the explosion probability of friction sensitivity of the corresponding formulations increased by 7.9-12.0 cm and 20%-28%， respectively. As the ADN/AP mass ratio increased， the peak temperature of exothermic reaction initially increased and then decreased. The highest exothermic peak temperature was observed when the mass ratio of ADN∶AP=1. When the mass ratio of ADN/AP≥1， the components in the formulations interacted intensely， resulting in a single sharp exothermic peak in a DSC curve. When the mass ratio of ADN∶AP=1， the formulation exhibited an impact sensitivity of 28.1 cm， a friction sensitivity of 32%， and a thermal decomposition temperature of 277.9 ℃. The combustion heat and detonation heat of the formulation were 13874.4 and 7666.9 kJ∙kg^-1， respectively.

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• Evolution laws of the thermal effect and shock wave generated by explosion of thermobaric explosive （TBX） around the tunnel entrance

  JI Yu-guo, HE Yong, TAN Yi-zhong, LI Jie, SHAO Lu-zhong, ZHANG Jun-nan, ZHANG Guo-kai, LI Gan

  2024,32(12):1287-1297, DOI: 10.11943/CJEM2024207

  Abstract(0) HTML(2) PDF(3.65 M)( 0)

  Abstract:To study the evolution laws and its suffered influential factors of thermal effect and shock wave generated by thermobaric explosive （TBX） explosion around the tunnel entrance， explosion experiments were carried out by varying the initial location of TBX relative to the tunnel entrance. Thermal effect parameters （e.g. fireball size and temperature）， and shock wave parameters （e.g. overpressure peak value， positive pressure duration， specific impulse and waveform）， were analyzed. Moreover， the propagation trace of shock wave inside the tunnel was analyzed in conjunction with the results of Trinitrotoluene （TNT） explosion experiments. The results indicated that， when the TBX charge was initiated at the tunnel entrance， both the thermal effect and shock wave effect in air explosion was better than that in a ground surface explosion. Regarding thermal effect， the height and peak temperature of the fireball generated by the explosion were approximately 2 and 1.41 times higher than that of a ground surface explosion， respectively. The peak temperature measured inside the tunnel was about 2.42 times higher than that of a ground surface explosion， and the heat flux density could exceed 19.3 times that of the ground surface explosion. The temperature increasement generated by the afterburning process of TBX indicated a positive correlation with the weight of TBX charge. Concerning shock wave， the overpressure generated by the afterburning process of TBX in air explosion at the tunnel entrance was stronger than that of the ground surface explosion. For air explosion， the reflection and superposition paths of shock wave were more sufficient. Compared to the ground surface explosion， the equivalent coefficients of overpressure peak value， positive pressure duration and specific impulse of the shock wave in air explosion were approximately 1.3， 1， and 1.1， respectively. The evolution laws of thermal effect and shock wave effect were influenced by the combination of the constraint from tunnel and the intervention of the ground. In air explosion， the constraint effect of tunnel was much more significant， so as to the afterburning effect. However， in a ground surface explosion， the intervention effect of the ground could weaken the constraint function of tunnel， so that the mixing between Al particles and air could be suppressed， resulting in a reduction of afterburning intensity.

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>Reviews

• Research Progress on the Influence of Aluminum Powder on the Typical Blast Damage Elements of Thermobaric Explosives

  LIU Wei, WANG Jing-yan, HAN Zhi-wei

  2024,32(12):1298-1313, DOI: 10.11943/CJEM2024143

  Abstract(0) HTML(0) PDF(2.40 M)( 0)

  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.

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>Preparation and Property

• Efficient Preparation of ADN/PDO Cocrystal and Characterization of the Structure and Properties

  LIU Ze-ning, QIAO Shen, MA Fan, YANG Zong-wei, YU Yan-wu

  2024,32(12):1314-1320, DOI: 10.11943/CJEM2024114

  Abstract(0) HTML(1) PDF(1.60 M)( 2)

  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.

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• Preparation of Iron-loaded Carbon Nanotubes and Catalysis of Energetic Components in Solid Propellants

  DU Xi-feng, YAO Ya-jing, ZHANG Xin-hui, ZHANG Yu-xin, HU Shuang-qi, FENG Yong-an

  2024,32(12):1321-1333, DOI: 10.11943/CJEM2024156

  Abstract(0) HTML(0) PDF(2.69 M)( 0)

  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.

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>Pyrotechnics

• A Prediction Model of Arc Ignition for Bridge Wire Electro Explosive Device Under Direct Current Excitation

  ZHANG Bo-yuan, LIANG Tao, XUE Wan-ting, WANG Zhe, MU Ya-ru, XIE Yan-zhao

  2024,32(12):1334-1342, DOI: 10.11943/CJEM2024163

  Abstract(0) HTML(2) PDF(1.58 M)( 2)

  Abstract:To investigate the arc ignition characteristics of bridge wire electro-explosive devices （EEDs） under DC excitation and predict the arc ignition safety threshold， the simulated charge method was exploited to calculate the cross-sectional electric field strength between the foot-wire and shell of bridge wire EEDs， following a scaled experiment for EEDs to solve unknowns in the electrical breakdown model， which is the electrical breakdown coefficient between the foot-wire and shell of EEDs， leading to a quantitative criterion and arc ignition prediction model. Results indicate that when the laboratory temperature is around 25° and the air pressure is atmospheric pressure， the distance between the foot-wire and shell of bridge wire EEDs significantly influences the arc ignition threshold，and the shorter the foot-shell distance is， the lower the arc ignition threshold is. The relative error between the measured breakdown voltage and the calculated results from the predictive model does not exceed 3.3%. Furthermore， the relative error between the foot-shell breakdown coefficient simulated in COMSOL and the calculated results from the predictive model is within 1%， verifying the model''s accuracy. This research provides a reliable tool for predicting arc ignition safety thresholds， potentially enhancing the design and safety of EEDs.

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• Nonlinear Amplification Effect and Ignition Experiments of Confined Charges under Multiple Impacts Loading

  ZHONG Su-yang, LIAO Shen-fei, HU Qiu-shi, LI Tao, FU Hua

  2024,32(12):1343-1351, DOI: 10.11943/CJEM2023245

  Abstract(0) HTML(0) PDF(2.10 M)( 0)

  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.

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