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ZHONG Su-yang, LIAO Shen-fei, HU Qiu-shi, LI Tao, FU Hua
Online:April 23, 2024 DOI: 10.11943/CJEM2023245
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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LI Sheng-wei, XU Dong, SUN Sen, ZHOU Jin-qiang, WU Cheng-cheng, GUO Xue-yong
Online:April 23, 2024 DOI: 10.11943/CJEM2024049
Abstract:In order to solve the problems of low density and effective oxygen content of the existing oxidant NH4ClO4 （AP） for mixed explosives， the oxidant KClO4 （KP） with higher density and oxygen content was compounded with AP， and the optimal ratio of AP/KP composite oxidant was determined by Molecular Dynamics. The novel AP/KP composite oxidant with high density and high oxygen release was prepared by physical mixing and solvent evaporation method， respectively， and its elemental composition， morphology， structure， composition and thermal properties were characterized by inductively coupled plasma spectrum generator （ICP）， scanning electron microscope （SEM）， X-ray powder diffractometer （XRD） and thermal analyzer （DSC-TG）. The results show that element and particle size distribution of the AP/KP composite oxidant prepared by solvent evaporation method is reasonable and uniform. The crystal form has not changed， and the crystal form is relatively complete， as proved by XRD. The thermal decomposition peak temperature of AP and KP was decreased by 11.25 ℃ and 13.87 ℃， respectively， which was more conducive to the thermal decomposition process. In addition， the composite oxidants prepared by physical mixing and solvent evaporation method were introduced into typical metal combustible agent Al powder， the ignition and combustion properties of samples prepared by different methods with Al powder were compared and studied. The results show that when the AP/KP composite oxidant prepared by solvent evaporation was mixed with Al powder， the combustion calorific value reached 12.228 MJ·kg-1， and the pressurization rate reached 5.21 MPa·s-1. The laser ignition test shows that the shortcomings of slow AP combustion reaction rate and difficult KP ignition were greatly improved.
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LIU Lei, WANG Ze-tao, LIU Yu-ji, TANG Yong-xing, HUANG Wei
Online:April 18, 2024 DOI: 10.11943/CJEM2024031
Abstract:Azo-bridged nitrogen-rich heterocyclic energetic compounds have high heat of formation and low mechanical sensitivity， making them widely applicable in the field of energetic materials. However， traditional preparation methods often involve oxidative coupling， suffering from high risks to safety and environment. In contrast， the electrochemical synthesis method is favored by researchers for its efficiency， controllability， and environmental friendliness. By adjusting the electrochemical reaction conditions， selective synthesis of azo-bridged nitrogen-rich heterocyclic energetic compounds with different structures can be achieved， opening up new possibilities for their synthesis. This study reviews the electrochemical synthesis methods， effects of electrolytes and electrodes， and possible reaction mechanisms of azo-bridged nitrogen-rich heterocyclic energetic compounds such as furazan， pyrazole， 1，2，4-triazole， and tetrazole. It is expected to provide a reference for the research and development of electrochemically synthesized azo-bridged nitrogen-containing heterocyclic energetic molecules.
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REN Jia-tong, CUI Peng-teng, ZHANG Heng, DING Feng, GAO Yu-chen, YANG Wei-tao
Online:April 18, 2024 DOI: 10.11943/CJEM2024076
Abstract:In order to explore the application prospect of a novel azido plasticizer 1，5-diazide-3-oxapentane （AZDEGDN） in gun propellant formulation， a semi-solvent method was adopted to prepare double- and triple-base gun propellants using AZDEGDN as the plasticizer， and the morphology， density as well as static combustion performance at different temperatures of AZDEGDN-containing propellants were studied. Results show that the AZDEGDN-containing double-base propellant （ADG-2） and triple-base propellant （ADG-3） without obvious defects in appearance can be prepared by semi-solvent extrusion process. SEM test shows that solid additives hexogen （RDX） and nitroguanidine （NGu） are uniformly distributed within ADG-3 propellant. The density of ADG-2 is 1.44 g·cm-3 and ADG-3 is 1.52 g·cm-3， both close to their theoretical density， indicating that the internal structures of AZDEGDN-containing propellants are relatively dense. The closed vessel tests demonstrate that the static combustion performances of both ADG-2 and ADG-3 propellants at room temperature （20 ℃） are stable. The burning rates increase evenly with the increase of pressure， without obvious turning phenomenon in burning rate-pressure curves （u-p curves）. The maximum combustion pressure of ADG-2 and ADG-3 propellants is 237.71 MPa and 263.80 MPa， and the burning rate pressure index is 0.9098 and 0.9754， respectively. The addition of RDX and NGu results in an increase of 15.5% and 10.9% in the burning rate pressure index of AZDEGDN-containing propellants in the low pressure range （50-100 MPa） and medium pressure range （100-150 MPa） respectively， while the burning rate pressure index in the high pressure range decreases by 4.2%. At high temperature （50 ℃） and low temperature （-40 ℃）， ADG-3 propellant can still keep stable combustion. The maximum combustion pressure changes from 263.80 MPa in room temperature to 265.92 MPa and 261.13 MPa， respectively. Besides， the combustion time changes from 14.70 ms to 13.52 ms and 16.40 ms respectively， and the burning rate pressure index changes from 0.9754 to 0.9464 and 0.9938 respectively. It is concluded that AZDEGDN-containing gun propellant is simple and mature in preparation method， dense and defect-free in structure， and also stable in static combustion performance， which is expected to become a kind of novel low-ablation gun propellant.
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YU Pei-dong, LIU Qiang-qiang, Ding Xiao-yong, LIU Ying-le, GAO Hai-xiang
Online:April 18, 2024 DOI: 10.11943/CJEM2024061
Abstract:The compound 5，7-bis（trifluoromethyl）-2-（dinitromethyl）-［1，2，4］triazolo［1，5-a］pyrimidine （
1 ） was designed， synthesized， and thoroughly characterized. Thermal properties were determined using Differential Scanning Calorimetry （DSC）， while Gaussian 03 and EXPLO5 v6.05 programs were employed to calculate the heat of formation and detonation properties of compound1 ， respectively. In addition， a comparative analysis of Hirschfeld surface， 2D fingerprint and electrostatic potentials （ESP） was conducted between compound1 and other known dinitromethyl-containing compounds in this study. The result demonstrate that compound1 exhibits exceptional insensitivity （IS > 40 J， FS > 360 N） toward external stimuli compared to other dinitromethyl-containing compounds. Furthermore， the presence of halogen bonding （C—F???X） effectively disrupts the formation of O…O interactions in energetic materials and leads to a favourable distribution of electrostatic potentials. This finding provides valuable insights for the development of novel insensitive energetic materials.- 1
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LIU Heng-yan, LIANG Zheng-feng, RUAN Xi-jun, CHENG Shu-jie
Online:April 17, 2024 DOI: 10.11943/CJEM2024023
Abstract:The distribution of initial fragment velocity in the aim direction is one of the important factors for evaluating the power of the directional warhead. Therefore， the calculation method of the initial fragment velocity in the whole domain on the directional side of the warhead under the eccentric double-line initiation and the kinetic energy gain compared with the central initiation are studied. Based on the infinitesimal theory， the calculation method of the initial fragment velocity in different circumferential position on the directional side was derived， and the static explosive experiment of the warhead was carried out to compare with the theoretical result. Combined with the numerical result of the warhead， the axial velocity correction function was fitted， and the universality of the algorithm was verified according to the existing research. It is shown that the proposed formula is suitable for the warhead with eccentric double-line initiation， and the error between theoretical calculation and test results is within 4.80%， calculation result is consistent with actual situation. The fitting correction function can predict the initial velocity of the fragments in different axial direction. The algorithm still has good universality when the warhead parameters change and the calculation error is less than 7.11%. Compared with central initiation， the eccentric double-line initiation mode with an angle of 60° can increase the total kinetic energy of the fragments in the range of -30°-30° from the center of the directional side by 34.9%.
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Online:April 17, 2024 DOI: 10.11943/CJEM2024039
Abstract:Two nitrogen-rich energetic salts， 5，5"-（hydrazine-1，2-diyl）bis（5，7-dihydro-［1，2，5］oxadiazolo［3，4-e］［1，2，4］triazolo［4，3-a］pyrimidine-8（4H）-one） perchlorate （
2 ） and 5，5"-（diazene-1，2-diyl）bis（［1，2，5］oxadiazolo［3，4-e］［1，2，4］triazolo［4，3-a］pyrimidine-8（7H）-one） nitrate （3 ） were accomplished from the raw material of 5，6-diamino-［1，2，5］oxadiazolo［3，4-b］pyrazine （1 ）. Structure characterization of energetic ionic salts2 and3 were achieved through various techniques， including Nuclear Magnetic Resonance Spectroscopy （NMR）， Fourier Transform infrared spectroscopy （FTIR）， elemental analysis （EA） and X-ray single crystal diffraction （XRD）. Their thermal decomposition behaviors were investigated using differential scanning calorimetry （DSC） method， while their friction and impact sensitivities were identified according to BAM standard test methods. Moreover， their detonation performances were predicted based on the combination of Isodesmic Reactions and EXPLO5 software. The results prove that compounds2 and3 crystallize in the monoclinic system， belonging to space groups Pn and P21/n， respectively. The cationic parts of their crystal structures show good planarity and intensive hydrogen bonds in the crystal packing are observed. The thermal decomposition temperatures of compounds2 and3 are respectively 154 ℃ and 130 ℃. Their theoretical detonation velocities are respectively 7722 m·s-1 and 8008 m·s-1， while their theoretical detonation pressures are respectively 26.3 GPa and 28.4 GPa. Their friction sensitivities are both 360 N， and impact sensitivities are greater than 40 J. Compounds2 and3 outperform traditional explosives TNT in terms of detonation performance， friction sensitivity， and impact sensitivity.- 1
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YAN Yi-teng, SUN Shan-hu, LIU Shan, JI Ying-xu, BAI Sen-hu
Online:April 08, 2024 DOI: 10.11943/CJEM2023262
Abstract:Branched glycidyl azide polymer （BGAP） has higher relative molecular mass， wider adjustment range of hydroxyl functionality （f）， higher heat of formation and lower viscosity than linear glycidyl azide polymer （GAP）. It can increase the energy level， and improve the processing and mechanical properties of the composite solid propellant. Therefore it has become a hot research topic in the field of the azido polyether binder. However， the essentially important key to obtain high quality BGAP energetic binder is how to control and regulate some structural parameters such as hydroxyl functionality， molecular weight and molecular weight distribution. This paper illustrates two synthetic methods and processes of BGAP， proposes the possible reaction mechanism， and summarizes the progress in performance research. Some problems and deficiencies are pointed out. Finally， the development prospects of BGAP in the field of synthesis and performance research are forecasted. It is concluded that optimizing the extraction procedure after reaction， improving the throughput per run， and strengthening the studies in fundamental performance and application will be the focuses in future researches.
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ZHANG Ye, WANG Xin-yu, XU Wen-yu, WANG Zai-cheng, JIANG Chun-lan
Online:March 28, 2024 DOI: 10.11943/CJEM2024010
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.
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JIANG Shuai-jie, QIN Ya-qi, XU Yuan-gang, LU Ming, WANG Peng-cheng
Online:March 27, 2024 DOI: 10.11943/CJEM2024028
Abstract:A novel nonmetallic salt， 3，5，7-triamino［1，2，4］triazolo［4，3-a］［1，3，5］triazine pentazolate （
4 ）， was synthesized through a metathesis reaction by employing AgN5 as precusor with 3，5，7-triamino［1，2，4］triazolo［4，3-a］［1，3，5］triazine hydrochloride. The structural characterization were carried out by X-ray single crystal diffraction， infrared spectroscopy （IR）， elemental analysis （EA）， nuclear magnetic resonance （NMR）， and thermal decomposition behavior were determined by thermogravimetric analysis （TG） and differential scanning calorimetry （DSC）. The enthalpy of formation of compound4 was calculated using atomization method， the detonation performance was predicted using EXPLO5， and sensitivity was tested using BAM testing method. The results show that compound4 exhibits a monoclinic crystal structure with a crystal density of 1.644 g·cm-3 and belongs to the P21/n space group. This compound has a nitrogen content of 77%， a thermal decomposition temperature of 113.8 ℃， and an enthalpy of formation of 491.5 kJ·mol-1. Furthermore， its detonation velocity was calculated at 7913 m·s-1， detonation pressure at 19.6 GPa； The impact sensitivities were measured >40 J， and friction sensitivity >360 N.- 1
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LIU Dan, WANG Jun-ru, ZHAO Xu, YANG Zhi-jian
Online:March 26, 2024 DOI: 10.11943/CJEM2023269
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.
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SHI Zhe, ZHAO Yuan-yuan, MA Zhi-wei, YANG Yu-lin, ZHANG Jian, WANG Xu-wen, LIANG Jia-yan
Online:March 22, 2024 DOI: 10.11943/CJEM2023268
Abstract:In order to solve the inhomogeneous component distributions and low combustion efficiency in the preparation process of nano-thermite， the core-shell structured nAl@Cu（BTC）/Fe（BTC） was prepared via a layer by layer assembly technique. The structure， morphology， thermal reaction performance （thermite-reaction temperature） and combustion performance （combustion time， ignition delay time， and combustion temperature， etc.） of nAl@Cu（BTC）/Fe（BTC） were studied. The results show that the thickness and morphology of the coating layer can be regulated during the layer by layer assembly process. As the thickness of the coating layer increases， the nano-thermite gradually changes from rough and loose to smooth and dense. The nano-thermite with alternating 12 layers of Cu（BTC）/Fe（BTC） possesses a severe burning effect with a fast flame propagation rate that reaches the maximum flame within 0.710 seconds. Besides， this sample also achieves a moderate ignition delay time （0.509 s）， the shortest combustion time （2.036 s）， and the highest combustion temperature （1425 ℃）. Meanwhile， its decomposition peak temperature of aluminum oxidation reaction can be reduced to 552.5 ℃ and 735.0 ℃ due to the synergistic effect of Cu（BTC） and Fe（BTC）.
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HE Xu-dong, ZHANG Zeng-ming, ZHANG Chao-yang, XUE Xiang-gui
Online:March 18, 2024 DOI: 10.11943/CJEM2023263
Abstract:The packing structure of energetic crystals is one of the important factors affecting their sensitivity. A crucial mechanism for reducing the sensitivity of energetic materials is buffering external stimuli through the slipping between molecular layers within the crystal. It is very important to understand the inherent relationship between the geometric shape of energetic molecules and their crystal properties for the better design of low sensitivity high energetic materials （LSHEs）. This study used neutral CHNO molecules containing nitro from the Cambridge Structural Database as samples. Hypothesis testing methods （including Z-， t-， and χ2 tests） were employed to investigate the correlation between the geometric shape of molecules and their crystal density， packing coefficient， and slipping ability. The study shows that among spherical， planar and linear molecules： spherical molecules have the highest crystal density and packing coefficient， but weaker slipping ability； planar molecules with high planarity achieve a crystal density comparable to spherical molecules by a high packing coefficient， while also exhibiting stronger crystal slipping ability， its confidence level of the χ2 test is close to 1； linear molecules perform less well than the former two. Though some crystals with high crystal density and packing coefficient do not have slipping ability， general speaking， the crystal density and packing coefficient of the crystals with slipping ability are higher than those without. Both Z-tests and t-tests indicate a confidence level exceeding 0.95， suggesting that designing crystal structures conducive to intermolecular-layer slipping is not contradictory to reduceing their sensitivity and increasing crystal density. Planar molecules have a higher crystal density than average， and it is strongly associated with crystal slipping ability， making them the preferred choice for designing LSHEs.
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CHENG Bing, WANG Hai-bo, CHENG Yang-fan, WANG Quan, LV Nao, HAN Ti-fei
Online:March 12, 2024 DOI: 10.11943/CJEM2023266
Abstract:To study the transfer characteristics of explosion energy released by the charge confined to tubes of different materials with lateral annular slits， explosion experiments were conducted involving charges with or without confinement to tubes of four materials. The high speed schlieren photographic system and shock wave overpressure monitoring system were employed to capture the propagation process of shock wave and obtain the distribution law of overpressure respectively， so that the explosion energy transfer law for the charges confined to tubes with lateral annular slits and the influence of tube material on its energy transfer characteristics were analyzed. The results showed that after the explosion of the charge confined to tubes with lateral annular slit， both the detonation product and shock waves firstly propagated outward towards the direction with slit， but the propagation towards the opposite direction is relatively delayed. Compared with the symmetric distribution of overpressure generated by a conventional cylindrical charge， the lateral annular slits in tubes could increase the overpressure in the direction with slit， but decrease that in the opposite direction. The asymmetric distribution of overpressure proved that the charge confined to tubes with lateral annular slits induced Munroe Effect in the slit direction. The hierarchy of Munroe Effect caused by lateral annular slits presented by materials： stainless steel （SS） > polyvinyl chloride （PVC） > fiber reinforced plastic （FRP） > plexiglass （PMMA）.
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WU Rui, XIAO Yi-jie, LI Qiang, YUAN Mao-bo, LIU Bo, ZHANG Yu-cheng
Online:March 07, 2024 DOI: 10.11943/CJEM2024033
Abstract:In order to investigate the thermal erosion characteristics and variation law of triple base propellant， various kinds of gun propellants with different components content were prepared. The erosion characteristics were determined through simulated test in a semi-closed bomb. The analysis reveals the impact of energy component and plasticizer content on gun propellant explosion temperature， and the impact of explosion temperature on erosion characteristics. The results indicate that changes in the explosion temperature of gun propellant， attributed to variations in cyclotrimetheylenetrinitramine （RDX）， nitroguanidine （NQ） and dioctyl phthalate （DOP） content， significantly affect erosion characteristics. An increase of 1% in RDX content results in an increase in explosion temperature by 0.59% and an increase in erosion rate by 1.23%. Compared with the absence of RDX， the erosion rate of 2% RDX-containing propellant increase 23.38%. Notably， an increase of 1% in NQ content reduces the explosion temperature by 0.23% and the erosion rate by 0.56%. An increase of 1% in DOP content reduces the explosion temperature by 2.99% and the erosion rate by 7.01%. For the triple base propellants within the range of explosion temperature from 2600-3100 K， an exponential relationship between the rate of erosion mass and explosion temperature is established， and characteristic coefficients of RDX， NQ， DOP system is given respectively， which is 0.106， 0.101， 0.163.
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HU Li-jing-cao, SUN Huan-yu, AN Zi-wei, ZHAO Zi-chang, HUANG Wei, LIU Yu-ji
Online:February 29, 2024 DOI: 10.11943/CJEM2023270
Abstract:5-amino-2H-pyrazol-3，4-dione-3-oxime-4-hydrazone （
3 ） and its perchlorate （4 ）， nitrate （5 ） and 5，5′-dinitramino-3，3′-azo-1，2，4-oxadiazolate salts （6 ） were prepared from 4-chloro-3，5-dinitro-1H-pyrazole via amination and substitution/reduction reactions. The single crystals of3 and4 were obtained by solvent evaporation method and the crystals were characterized by single crystal X-ray diffraction. The structures of energetic compounds3 -6 were characterized by nuclear magnetic resonance spectroscopy and infrared spectroscopy. Moreover， the capacities of those compounds were confirmed by gas pycnometer， differential scanning calorimetry， impact and friction sensitivity testers. Their enthalpies of formation and detonation parameters were estimated using theoretical calculation methods. The results show that3 has a planar molecular configuration. The ketone oxime and ketone hydrazone have unique double bond characteristics， reducing the conjugation of the pyrazole ring and making it easier to form salts. After salt formation， different anions have various effects on the performance of the neutral compound. Among those examined anions， the perchlorate anion not only improves the oxygen balance， but also increases the density， resulting in the detonation velocity and pressure of4 （8499 m·s-1 and 30.2 GPa） higher than3 （8072 m·s-1 and 22.5 GPa）. In addition， 5，5′-dinitramino-3，3′-azo-1，2，4-oxadiazole significantly increases the decomposition temperature of3， rising from 135 ℃ to 285 ℃. These results indicate that a rational combination of anions and cations can effectively regulate the performances of target energetic compound.- 1
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LIU Jun, LIANG Shuang, LIU Xiang-yang, GAO Jie
Online:February 26, 2024 DOI: 10.11943/CJEM2023236
Abstract:To reveal the relationship between the evolutions of polymer chains within the NEPE propellant matrix and the hyperelastic mechanical behavior， a multiscale approach was adopted to investigate the evolution behavior and characterization model of polymer chains under different deformation states. Firstly， based on the microscopic models of components such as matrix adhesives， curing agents， and plasticizers， a dynamic model describing the evolution of cross-linked and free chain configurations under complex deformation states was developed through molecular dynamics simulation of the matrix system Subsequently， the free energy contributed bycrosslinked and free chains was quantitatively characterized based on statistical mechanics， and a hyperelastic constitutive model considering the cross-linking and entanglement effects was established. Finally， the developed constitutive model was validated by using the quasi-static tensile experimental data of NEPE propellant matrix samples. Compared with the classical Arruda-Boyce model， the constitutive parameters in the present model have real physical significances and can be obtained by experimental methods， which enables the present model to better predict the hyperelastic behavior of the propellant matrix under different deformation states， and thus provide model for the regulation of mechanical properties and component optimization of propellant matrix.
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XUE Hui-hui, HUANG Juan, ZHANG A-lei, CHEN Ke-quan, ZHOU Jie, DING Ya-jun, XIAO Zhong-liang
Online:February 03, 2024 DOI: 10.11943/CJEM2023203
Abstract:A green non-toxic， easy and accuracy analysis method of the nitrogen content in nitrocellulose （NC） was investigated by using ultraviolet spectrophotometer， which was based on a linear relationship between the nitrogen content of NC and the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis. Under the same reaction condition， five NC standard samlpes with known nitrogen contents were hydrolyzed. The concentrations of NO2- and NO3- in the hydrolysate were measured by the ultraviolet spectrophotometer， and the reaction condition of measuring system was optimized. The linear relationship between the nitrogen content of NC standards （x） and the molar ratio of nitrite-to-nitrate ions （y） was determined by the least squares method. Finally， three NC samples were used to evaluate the proposed method. Results show that the concentration of NO2- and NO3- in alkaline hydrolysate can be measured simultaneously by ultraviolet spectrophotometer， and the most suitable reaction condition is as follows： the concentration of sulfamic acid of 20 g·L-1， and the process time of 30 min. Under the optimal reaction condition， the linear relationship between x and y is obtained， and the R2 is 0.9893. The verification results of NCA， NCB and NCC reveal that the nitrogen content determined by ultraviolet spectrophotometer and actual nitrogen contents are in good agreement. The relative standard deviation （n=4） values are all less than 0.150%.
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YANG Ya-lin, QIN Yi-feng, XIA Jiang-lu, DU Hui-ying, LI Xin-yu, WU Bo, MA Cong-ming
Online:January 30, 2024 DOI: 10.11943/CJEM2024006
Abstract:Polycyclic energetic compounds with high nitrogen content have attracted much attention owing to their distinctive advantages in constructing novel energetic molecules with low mechanical sensitivity， good thermal stability and high density. The construction of polycyclic skeletons involves the incorporation of tetrazole into fused heterocycle， serving as high-energy organic fuel and hydrogen bond donors. Three self-assembled non-hydrated energetic compounds， namely 7-amino-6-（2H-tetrazol-5-yl）-pyrazolo［1，5-a］pyrimidine （
1 ）， 7-diamino-6-（2H-tetrazol-5-yl）-［1，2，4］triazolo［1，5-a］pyrimidine perchlorate（2） ， and 2，7-diamino-6-（2H-tetrazol-5-yl）-［1，2，4］triazolo［1，5-a］pyrimidine perchlorate（3）， were synthesized through noncovalent self-assembly of polycyclic skeleton with the oxidizing structural unit HClO4 rich in hydrogen bond acceptors. The structural characterization employed Nuclear Magnetic Resonance Spectroscopy and single crystal X-ray diffraction， while thermal behaviors and mechanical sensitivities were determined by differential scanning calorimetry-thermogravimetry and BAM methods. Detonation performances were predicted utilizing the Gaussian 09 program and EXPLO5 V6.05.02. The results show that three compounds exhibit high crystal densities （ρ： 1.75-1.86 g·cm-3）， good thermal stabilities （decomposition temperature （onset）： 184-260 ℃）， and good detonation performances （detonation velocity： 7343-7570 m·s-1； detonation pressure： 21.1~22.8 GPa）， surpassing those of traditional explosives trinitrotoluene （TNT）. Both compound1 （impact sensitivity （IS） > 40 J， friction sensitivity （FS）=216 N） and compound3 （IS=25 J， FS = 240 N） exhibit low mechanical sensitivity.- 1
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WEN Yi-meng, MAO Jun-qing, MA Song-yu-chen, DI Yang, LIU Tao, LIU Jie
Online:January 25, 2024 DOI: 10.11943/CJEM2023200
Abstract:Due to contacts with additives or changes of environmental conditions （temperature or pressure）， the polymorphism hexanitrohexaazaisowurtzitane （CL-20） is easy to transform into mixed crystal form in propellant system， which leads to structural damage and performance degradation of the propellant. In order to hinder the contact between the solvent and CL-20， then inhibit the crystal transformation of CL-20， the polyphenol amine （PCHA） film was prepared based on the oxidative self-polymerization of hexamethylenediamine （HMDA） and catechol （CCh）. The surface of CL-20 crystal was modified by water suspension method under mild conditions. The scanning electron microscopy （SEM）， Fourier transform infrared spectroscopy （FT-IR）， Raman spectroscopy （RAMAN）， X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS） were used to study the morphology， coating content， thermal properties， and stability in ethylene glycol solution for the composite particles. The results show that HMDA and CCh can modify the surface of CL-20 crystal under mild conditions and form a dense PCHA coating layer. The content of PCHA is about 1% measured by dissolution weighing method and high performance liquid chromatography （HPLC）. The PCHA coating layer increases the crystal transition and thermal decomposition temperature by 16 ℃ and 7 ℃， respectively. The thermal decomposition activation energy Ea at different heating rates was calculated by Kissinger method. The activation energy of CL-20@PCHA is about 8 kJ·mol-1 higher than that of CL-20， and the thermal stability is greatly improved. The XRD test results indicate that the PCHA film can effectively prevent the contact between the solvent and CL-20， slow down the dissolution rate of CL-20 in the solvent， and effectively inhibit the crystal transformation of CL-20.
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PAN Chang-xin, LIU Feng, BI Ru-jie, DAI Wei, ZHU Zheng-de, CHENG Yu-hang
Online:January 17, 2024 DOI: 10.11943/CJEM2023219
Abstract:In order to study the effect of high pressure from screw pumping and medium deep hole charging on the microstructure and thermal stability of the on-site mixed emulsion explosive matrix， the microstructure， particle size distribution， crystallization content， thermal decomposition process， thermal decomposition reaction activation energy， thermal decomposition mechanism function and rate equation of the matrix under atmospheric and high pressures were studied by optical microscope， laser particle size analyzer， water solubility experiment， thermogravimetry and derivative thermogravimetry （TG-DTG） couple method， Kissinger method and Ozawa method， Coats-Redfern method and ?atava method. The results show that from atmospheric pressure to high pressure， polymerization， demulsification and crystallization of the intra-matrix phase droplets appeared， the particle size increased from 3.717 μm to 4.474 μm， the precipitation amount of ammonium nitrate crystals increased from 0.0530 g to 0.0640 g， and the uniformity of the emulsion system was weakened. The average thermal decomposition onset temperature of the matrix Tonset increased from 157.4 ℃ to 184.0 ℃， the average first-order derivative thermogravimetric peak temperature Tp increased from 262.6 ℃ to 281.8 ℃， the average mass loss rate increased from 0.1454 %·s-1 to 0.1476 %·s-1， and the reaction activation energy decreased from 108.49 kJ·mol-1 to 84.74 kJ·mol-1. The free water released by evaporative demulsification under high pressure might cause the rise of Tonset and Tp， and the thermal decomposition reaction was more likely to occur. The activation energy calculated by the Ozawa method had a different trend with the increase of conversion rate， and the thermal decomposition reaction mechanism function changed from Valensi equation to inverse Jinder equation and the rate equation also changed. The high pressure promotes the process of droplet polymerization， demulsification and crystallization of the intra-matrix phase， reduces the activation energy of the thermal decomposition reaction， and weakens the homogeneity and thermal stability of the system.
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Online:January 05, 2024 DOI: 10.11943/CJEM2023206
Abstract:In order to understand the ignition process of plasma jet in the liquid propellant electrothermal chemical gun， the spreading characteristics of plasma jet in simulative liquid propellant LP1846 were studied. A two-dimensional axisymmetric unsteady mathematical model of plasma jet spreading in the liquid was established， and the model was validateded with the experiments based on the liquid working medium of water. On this basis， the spreading process of plasma jet in the simulative liquid propellant LP1846 was numerically simulated. The morphological changes of plasma jet and the distribution characteristics of pressure， velocity and temperature in the jet field were analyzed. Results show that when the plasma jet expands in the simulative liquid propellant LP1846， there is turbulent mixing phenomenon due to Taylor-Helmholtz instability， and it becomes more and more intense. It is manifested by the protruding head of the jet and the axial elongation to form a tip， and the jet entrains the simulative liquid propellant medium to produce droplets in Taylor cavity， and the number of droplets gradually increases. At the same time， the necking phenomenon occurs near the nozzle hole during the expansion of plasma jet due to the simulative liquid propellant backflow. The jet field fluctuates due to the alternating action of expansion and compression waves， especially near the nozzle hole. The pressure field shows alternating distribution of high and low pressures， and the velocity field also shows similar distribution.
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HUANG Qi, LIU Li, JIN Bo, PENG Ru-fang
Online:December 31, 2023 DOI: 10.11943/CJEM2023169
Abstract:A new energetic iron-oxygen cluster， ［Fe2Ⅲ（μ2-CH3O）（μ3-OH）（μ2-O）（BODTO2-）（H2O）］4 （
1 ）， was synthesized by solvothermal method using 5，5"-｛［3，3"-bis（1，2，4-oxadiazole）］-5，5"-yl｝-bis（1-hydroxytetrazole） as ligand. The structure and thermal stability of compound1 were studied by single-crystal X-ray diffraction， differential scanning calorimetry and thermogravimetric analysis. The catalytic performance of compound1 on the thermal decomposition of ammonium perchlorate （AP） was also investigated by differential thermal analyzer. Compound1 crystallizes in cubic I-43d space group with a density of 1.506 g·cm-3. In the crystal structure， the nearby Fe3+ cations are interconnected to each other by bridging oxygen atoms. Through those connections， the iron（Ⅲ） cluster cages are formed. The peak thermal decomposition temperatures of compound1 are 513.9 K， 617.6 K and 669.4 K， respectively. The detonation velocity and detonation pressure of compound1 are 6.94 km·s-1 and 19.09 GPa， respectively. In addition， the impact sensitivity and friction sensitivity of compound1 are 15 J and 360 N， respectively. After adding 10% compound1 to AP， the high temperature decomposition temperature of AP decreases by 65 K， and the decomposition activation energy decreases by 82.2 kJ·mol-1， demonstrating the high catalytic activity of compound1 for the thermal decomposition of AP and the great potential of compound1 for application in energetic combustion catalysts.- 1
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DU Hui-ying, QU Zhi-hui, XIA Jiang-lu, YANG Ya-lin, LI Xin-yu, QIN Yi-feng, WU Bo, MA Cong-ming
Online:December 26, 2023 DOI: 10.11943/CJEM2023201
Abstract:1，3，5，5-Tetranitro-hexahydropyrimidine （DNNC） and 1，4，6，6-tetranitro-1，4-diazepane （TNDA） were synthesized from the reaction of 2，2-dinitropropane-1，3-diol with tert-butylamine and ethylenediamine， respectively. Their structures were characterized by nuclear magnetic resonance （NMR）， fourier infrared spectroscopy（FT-IR）， and single crystal X-ray diffraction. Meanwhile， their thermal behaviors and mechanical sensitivities were determined by differential scanning calorimetry-thermogravimetry（DSC-TG） and the BAM methods. Furthermore， isodesmic reactions and EXPLO5 were used to predict detonation parameters. The crystal structures indicate that the cyclohexane skeleton in DNNC and the cycloheptane skeleton in TNDA are both chair conformations. Both of them have extensive intermolecular and intramolecular non-classical hydrogen bonds. The results of DSC-TG show that the phase transition temperatures of DNNC and TNDA are 155.0 ℃ and 154.5 ℃， respectively. Furthermore， their peak decomposition temperatures are 215.3 ℃ and 205.9 ℃. In addition， DNNC and TNDA possess good mechanical sensitivity. Their impact sensitivities are 25 J and 17.5 J， and friction sensitivities are 144 N and 240 N. Besides， their theoretical detonation velocities are 8772 m·s-1 and 7828 m·s-1， and detonation pressures are 34.8 GPa and 25.0 GPa.
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LV Liang-liang, ZHANG Wei-bin, LI Gong-ping, PAN Xiao-dong, ZHANG Cai-xin, YANG Ya-fei, ZHANG Cui
Online:December 12, 2023 DOI: 10.11943/CJEM2023212
Abstract:The performance and dependability of PBX are significantly impacted by internal cracks. Accurate crack identification and quantitative analysis are crucial to evaluate the performance of PBX. Currently， the ability to identify and quantitatively analyze internal cracks of PBX needs to be further improved. Consequently， research on a deep learning-based method for PBX crack identification was conducted. Based on the popular deep learning networks， five different deep learning network structures were designed. This study aimed to compare the effects of network type， connection style， and pre-trained models on the recognition of PBX cracks. Internal crack images of PBX were obtained by CT technique. The training dataset of network was constructed using these crack images. The crack dataset was used to train five different types of networks. The performance of five networks was assessed based on Accuracy， F1， and MIoU. Select an outstanding network for PBX crack recognition and training based on the findings. The results indicate that， U-Net outperforms Seg-Net in pixel-level crack recognition and the Concatenate operation preserves more features compared to the Pooling Indices method. The pre-trained model （MobileNet and ResNet） can improve the training speed of the network， but its crack pixel-level recognition performance is reduced. The proposed method was applied to identify PBX crack， achieving pixel-level recognition. The results include a crack detection rate of 0.9570， a single pixel recognition accuracy of 0.9936， an MIoU of 0.9873， and a relative crack area of 0.7585， demonstrating superiority over traditional image segmentation methods.
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CAI Jing-jing, XU Xuan, CHEN Zhan-yang, YANG Jun
Online:December 07, 2023 DOI: 10.11943/CJEM2023196
Abstract:In order to explore the influence of the radial air gap in the hole on the directional penetration effect of shaped charge with/without metal liner and the detonation energy transfer process of explosive， ANSYS/LS-DYNA software was used to carry out the numerical simulation study when the air gap of the charge in the hole was 6， 8， 10， 12， 14 cm. The process of centralized release of energy from the shaped charge with metal liner forming an EFP and without metal liner forming concentrated detonation product flow as well as the depth of directional penetration into the borehole wall， was analyzed. The results show that when the air gap is less than 10 cm， the penetration depth of concentrated detonation product flow into the hole wall is increased by 53% （6 cm） and 29% （8 cm）， respectively， compared with the average penetration depth of EFP. When the air gap was greater than 10 cm， the average penetration depth of EFP increased by 26% （12 cm and 14 cm） compared with the concentrated detonation product flow. The kinetic energy of EFP and concentrated detonation product flow per unit area through the hole wall on the shaped energy axis was calculated， it is found that when the air gap is small， the energy dissipation of concentrated detonation product flow in the air is less than that of EFP plastic deformation， and the penetration effect of concentrated detonation product flow on the hole wall is better. When the air gap is large， the density and kinetic energy at the axis of the concentrated detonation product flow are significantly reduced due to the spatial expansion of detonation products， while the EFP has high density and incompressibility， small energy dispersion and slow decay of kinetic energy， so the penetration effect of EFP on the hole wall is better than that of the concentrated detonation product flow.
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YAN Xiao-hong, XU Chuan-hao, LI Qian-bing, NIU Kang, GAO Lei, AN Chong-wei, WANG Jing-yu
Online:March 25, 2024 DOI: 10.11943/CJEM2024040
Abstract:In order to explore the feasibility of combining emulsion explosive ink and inkjet printing process， an oil-in-water （O/W） two-component binder system was designed through ethyl acetate solution of fluorocarbon resin （FEVE） as oil phase and polyvinyl alcohol （PVA） aqueous solution as water phase. The micro-nano HMX was selected as the main explosive to prepare O/W suspension explosive ink for the inkjet printing. Furthermore， the density， morphology， mechanical properties， thermal safety performance， impact sensitivity and friction sensitivity of the printed samples were characterized by electron density tester， laser confocal microscope， scanning electron microscope （SEM）， X-ray diffractometer （XRD）， nanoindentation instrument， simultaneous thermal analysis TG-DSC， impact and friction sensitivity tester. The detonation velocity and critical size of the printed samples were tested. The results show that the surface of the inkjet printed sample is relatively flat， the average line roughness is 7.346 μm， and the internal particle distribution is compact. The crystal type of HMX particles would not change during printed process， and the printed samples display good the thermal stability and the mechanical properties. The measured density of the sample is 1.5326 g·cm-1 （83% theoretical maximum density）. The impact energy and the friction load of the printed sample are 7 J and 144 N， respectively. The detonation velocity of the printed sample with size of 1 mm×1 mm is 7076 m·s-1 and the critical size is 1 mm×0.087 mm. Therefore， the samples prepared through inkjet printing of HMX based emulsion explosive ink have excellent safety performance and micro-scale detonation performance.
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SHAN Jun-Peng, WANG Shan, DENG Peng-Fei, TANG Wei, WEN Qian-Qian
Online:April 07, 2024 DOI: 10.11943/CJEM2024029
Abstract:The apparent fracture toughness Kc is an important material property that characterizes the ability to resist crack initiation and propagation in the polymer bonded explosive （PBX）， investigating the size effect of apparent fracture toughness Kc is of great significance for predicting the crack initiation and failure behavior of PBX at different scales. This study examines the size effect characteristics of the apparent fracture toughness Kc of PBX surrogates by cracked straight through Brazilian disk （CSTBD） tests. Fracture tests were conducted on CSTBD specimens to investigate the influence of pre-existing crack lengths （2， 4， 6， 8， 10 mm） on the apparent fracture toughness Kc. The size effect of the apparent fracture toughness Kc of PBX surrogates was explained using the traditional maximum tangential stress （MTS） criterion and the modified maximum tangential stress （MMTS） criterion， which considers the higher-order coefficients of Williams series and the length estimation model of fracture process zone （FPZ）. Results show that， as the crack length increases， Kc increases from 0.139 MPa·m0.5 to 0.251 MPa·m0.5， and Kc tends to stabilize with the increase in crack length. With the use of the A3 term-corrected FPZ length estimation model， the modified maximum tangential stress （MMTS） criterion can effectively explain the size effect of the apparent fracture toughness Kc of PBX surrogates compared to the traditional maximum tangential stress （MTS） criterion.
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YUE Hong-li, ZHANG Cui, ZHANG Wei-bin
2024,32(4):345-352, DOI: 10.11943/CJEM2023157
Abstract:The molding granule is an intermediate for polymer-bonded explosive （PBX） components. Characterization of the physical parameters of granular system is of great significance to understanding the influence of different granule structure on the performance of PBX components. X-ray computed micro-tomography （XCT） and CT image processing were used to non-destructively characterize physical parameters （including granule diameter， volume fraction， porosity， sphericity and intrinsic density） of the granular random packing systems. The average granule diameter of granular systems is up to 1.04 mm， the volume fraction is up to 68.7%， the lowest porosity is 1.04%， the highest average sphericity is 0.93， and the highest density is 1.44 g·cm-3. Results show that the type of binder， composition and ratio of explosive crystals， and granulation process have a pronounced influence on the physical parameters of granular packing systems. Moreover， there is a correlation between physical parameters of granular systems. The more dispersed diameter distribution of granular system leads to the larger the average surface area of granules. The larger average granule diameter and lower average sphericity of granular system result in the higher porosity of the granules. The volume fraction of granular systems with larger average granule diameter is higher， and the volume fraction of the granule accumulation is independent of the sphericity when the average sphericity is large. This research provides fundamental insights into understanding the physical parameters and their associations with material properties in molding granular packing systems.
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Gan Ren-jie, YU Li-da, LI Hai-ning, ZHANG Wei-bin, LI Wei-bin, YANG Zhan-feng
2024,32(4):353-359, DOI: 10.11943/CJEM2023198
Abstract:The internal crack detection of polymer bonded explosive （PBX） is of great significance and engineering application value for its safety and structural integrity evaluation. In order to improve the imaging detection accuracy and image quality of PBX internal crack defects， the curved surface modified water immersion ultrasonic total focusing imaging method was proposed. On this basis， the delay multiply and sum （DMAS） technology was further combined. The ultrasonic imaging detection of the bottom crack defects of the Φ100.0 mm semi-cylindrical PBX was studied by water immersion method， and high-precision imaging characterization and high signal-to-noise ratio imaging of this bottom crack defect of the curved PBX was realized. The experimental results show that the crack defect height measurement error of the traditional TFM imaging algorithm is 12.0%， and the image signal-to-noise ratio is 1.37 dB. The height measurement error of this crack defect after surface correction is 3.6%， and the image signal-to-noise ratio is 2.13 dB. The crack defect height measurement error of the surface correction algorithm combined with DMAS is only 0.4%， and the image signal-to-noise ratio is 5.32 dB.
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LIANG Peng-fei, CHEN Jin-fang, ZHAO Mei-ling, ZHANG Guo-hui, WANG Ya-li
2024,32(4):360-368, DOI: 10.11943/CJEM2023078
Abstract:Atomization performance of free impinging jets with unequal nozzle diameter of 60% Glycerol-water （60G） solution was investigated using PIV technique. The liquid sheet breakup characteristics and droplet behaviors were studied under different Weber numbers （51≤We≤1605）， jet velocities （2.12 m·s-1≤u≤6.37 m·s-1） and nozzle diameters （nozzle 1： left nozzle diameter （D1）=1.5 mm， right nozzle diameter （D2）=2 mm； nozzle 2： D1=2 mm， D2=3 mm）. The droplet distribution of the composite energetic material binder solvent diethylene glycol-water solution was also investigated. The results show that， as We number increases， liquid sheet breakup length increases first and then decreases from edge-free mode （M3） beginning， the liquid sheet thickness and droplet diameter decrease while the droplet velocity increases. Nevertheless， as the nozzle diameter increases， changes in liquid sheet breakup mode are insignificant， and the liquid sheet breakup length， thickness and droplet diameter all increase， while the droplet velocity decreases. At the same time， the empirical correlation equations are obtained between liquid sheet breakup length， liquid sheet thickness， Sauter mean diameter D［3，2］ and nozzle diameter， We number. After validation using the diethylene glycol-water solution， it reveales that with the increase of jet velocity， the droplet diameter decreases and the distribution becomes narrow after the impinging of diethylene glycol-water solution. The error range of D［3，2］ values is within ±15% of the empirical correlation equation， which is consistent with the theoretical prediction results.
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XIA Wen-tao, DU Fang, LI Yi-heng, LIN Li-yun, QU Wei-chen, QIN Rui, TAO Bo-wen, GU Jian
2024,32(4):369-376, DOI: 10.11943/CJEM2023230
Abstract:In order to investigate the combustion characteristics of Al powders in NOx， the reaction mechanism of Al with three nitrogen oxides （NO2， NO and N2O） was studied by means of density functional theory ωB97X. Firstly， the geometries of reactants， intermediates， transition states and products were optimized with all parameters. The authenticity of intermediates and transition states was confirmed by frequency analysis. The transition states were further determined by intrinsic reaction coordinates （IRC） calculation， and then the detailed reaction paths and mechanisms were obtained. High precision single-point energy of each structure was obtained by using the double hybrid functional PWPB95 combined with DFT-D3 correction and def2-TZVPP basis set. The rate constants of the related reactions were calculated by using the variational interpolation transition state theory， and the Arrhenius expressions for each reaction are obtained. The results show that the reaction process of Al with NO and NO2 is that Al and O atoms join together to form the intermediate of the complex， and then break the N─O bond through the ternary ring transition state to form the product. When Al reacts with N2O， Al reacts with N atoms to form a complex and then the elimination reaction takes place through the ring transition states. The activation energies of the reaction of Al with NO2， NO and N2O are 4.3 kJ·mol-1，249 kJ·mol-1 and 13.4 kJ·mol-1， respectively. From 2400 K to 4100 K， the reaction rate of Al with NO2 and N2O is higher than 106 m3·mol-1·s-1， which indicates that the reaction is easy to take place and the reaction rate is very fast， and the reaction rate of Al with NO is about 1/10000 of that of Al with NO2 and N2O.
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DING Zhi-hao, YANG Wei-tao, GAO Yu-chen, YANG Jian-xing, KONG Xin, YANG Bin
2024,32(4):377-386, DOI: 10.11943/CJEM2023110
Abstract:To study the effects of extrusion system nozzle runner structural parameters （cone angle， outlet diameter， and molding section length） on the fluid flow of energy-containing material extrusion process in the direct-in-writing-forming （DIW） technology， an extrusion model of high-viscosity energy-containing materials based on the Polyflow Extrusion module was established， and was verified by extrusion experiments under the working conditions of direct-write 3D printing. The study analyzed the effects of cone angle range （90°-130°）， outlet diameter （0.75-2 mm）， and molding section length （5-20 mm） on the extrusion process of high-viscosity energy-containing materials through the established model. The results show that the Polyflow Extrusion module can accurately simulate the flow behavior of composite energy-containing materials. When the cone angle is 100°， and the nozzle outlet diameter is between 1.5 mm and 1.75 mm， the extrusion process is relatively stable with small extrusion expansion. Additionally， as the length of the molding section grows， the required inlet pressure increases while the outlet expansion effect decreases.
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CHEN Rong, MA Rong, WANG Zheng, REN Ke-rong, ZHANG Si-yuan, TIAN zhan-dong
2024,32(4):387-396, DOI: 10.11943/CJEM2023133
Abstract:The cast TiZrNbV refractory high entropy alloy （RHEA） has high structural strength and good energy release characteristics. As an energetic structural material， it needs to withstand complex dynamic load environments in engineering applications. Studying the spalling behavior of TiZrNbV refractory high entropy alloy and obtaining accurate dynamic constitutive parameters are vital for its engineering application. The spalling characteristics of TiZrNbV RHEA were studied by flat plate impact experiment using a 20mm light gas gun. Parameters such as spalling strength， Hugoniot elastic limit （HEL）， and plastic strain rate were obtained， based on the free surface velocity history. The recycled specimens were analyzed using scanning electron microscopy （SEM）， and the spalling characteristics of TiZrNbV RHEA at different strain rates were analyzed from both macro and micro perspectives. It was shown that the geometrically necessary dislocation of the samples significantly increased with the increase of loading velocity. The spalling strength of TiZrNbV RHEA increases with the loading strain rate and the loading stress， with values ranging from 0.93 GPa to 2.23 GPa. The GTN-JC constitutive model parameters of TiZrNbV RHEA were obtained by calibrating the free surface velocity history of the spallation experiment with a flyer velocity of 580 m·s-1. The spallation behavior of the sample under 610 m·s-1 flyer velocity loading was calculated by using the fitted parameters. It was indicated that the free surface velocity curve of the spallation experiment performed well in simulating the spallation behavior of coarse-grained TiZrNbV RHEA. The simulation results show that the free surface velocity curve is consistent before the first tensile stage， which can be used for the dynamic analysis of sample spalling failure. The obtained parameters can provide reference for the engineering application of TiZrNbV RHEA.
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LI Si-han, WANG Ke-jian, NIU Yu-lei, HUANG Han-zhe, MA Zi-yu
2024,32(4):397-407, DOI: 10.11943/CJEM2023209
Abstract:In order to study the quasi-static compression behavior of polymer bonded explosive （PBX）， the uniaxial quasi-static compression tests were carried out on two typical PBX substitute materials （with and without aluminum powder） at different strain rates， and their mechanical properties were compared and analyzed. Based on the Zu-Wang-Tang （ZWT） model， a new model was proposed to describe the quasi-static compression behavior of materials. The constitutive model parameters were obtained by genetic algorithm， and the model was developed by using Fortran language in the User Material （UMAT） subroutine interface of Abaqus finite element analysis software. Results show that the quasi-static compression process of casting PBX substitute materials can be divided into three stages： elastic compression， stress decay and instability failure. The mechanical behavior of quasi-static compression is obviously correlated with the strain rate. With the increase of the strain rate， the effective compressive strain of the material is basically unchanged， while the logarithms of compression modulus， yield strength and compressive strength are linearly related to the logarithm of strain rate. The addition of aluminum powder can improve the compression modulus， yield strength and compression strength of casting PBX substitute materials. The newly constructed constitutive model can better describe the quasi-static compression behavior of casted PBX substitute materials， and its universality is validated by the finite element analysis software. The coefficients of determination （R2） between the simulated and experimental results are higher than 0.98， indicating a high level of consistency.
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LIU Rui, LIU Jian, TANG Yue-chuan, ZHANG Chao-yang, HUANG Jing, HUANG xin
2024,32(4):408-421, DOI: 10.11943/CJEM2023226
Abstract:The explore of energetic molecules faces multiple challenges， and the traditional design method are inefficient. The emergence of computer-aided molecular design has changed the research and development model. This review provides an overview of the development of energetic molecular design and introduces the current research status of computer-aided energetic molecular design. By summarizing the latest advancements in Artificial Intelligence （AI） technology across various design aspects， including performance prediction， molecular generation， retrosynthetic reaction prediction， and reaction condition prediction， we discussed the existing gap between the current approaches in energetic molecular design and other materials design methods. By thinking about the causes of the gap， we present an outlook on the future developmental directions of AI-assisted energetic molecular design. Research indicates that AI has already been applied in property prediction and molecular generation of energetic molecular design， but requires further exploration in retrosynthetic reaction prediction， and reaction conditions prediction. AI-assisted design of energetic molecules holds broad promising application prospects. Data enhancement， transfer learning and high-throughput computing are expected to solve the problem of weak data of energetic molecules. Enhancing AI-assisted prediction of synthesis routes and reaction conditions for energetic molecules shows promise for achieving the automatic molecular design via whole process of “design→evaluation→preparation→verification”. AI-assisted energetic molecular design provides new possibilities for improving the level of energetic molecular design and helps to improve the efficiency of energetic molecule research and development.
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ZHAO Yang, JIN bo, PENG Ru-fang
2024,32(4):422-434, DOI: 10.11943/CJEM2023177
Abstract:In order to utilize the performance advantages of carbon nanomaterials， this article summarizes the application of carbon nanomaterials in the desensitizing technology of energetic materials. The effects of typical carbon nanomaterials， such as graphite， carbon nanotubes， graphene and its derivatives， fullerene and its derivatives， on the reduction of impact， shock wave， and friction sensitivity of energetic materials， and explored the desensitization mechanism of different carbon nanomaterials was discussed. Finally， the development prospect of carbon nanomaterials in this field of desensitizing technique of energetic materials is forecasted. It is considered that optimizing the preparation process of carbon nanomaterials and energetic materials， deeply understanding the properties of carbon nanomaterials and conducting functional modification， regulating the interface interaction between carbon nanomaterials and energetic materials and further exploring the desensitization mechanism of carbon nanomaterial will be the focus of future research.
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WANG Zhe-jun, QIANG Hong-fu, WANG Jia-xiang, PEI Shu-di, LI Shi-qi, GENG Ting-jing, HAN Yong-heng
2024,32(4):435-464, DOI: 10.11943/CJEM2024014
Abstract:The damage behaviors of composite solid propellants were reviewed from four aspects： micro scale， meso scale， macro scale and cross scale. During this process， the observation and characterization methods of damage at different scales， determination methods for damage thresholds， construction methods for damage evolution models， numerical simulation methods for damage， and macro-mesoscopic cross-scale analysis methods were summarized. Based on this， to several shortcomings in current research， the future research directions that need to be further focused on are as follows： expanding the range of influencing factors to be considered in numerical simulation of damage behaviors for composite solid propellants at the microscale， and strengthening the verification of simulation results with experimental research conclusions from multiple aspects； improve the observation ability of damage experiments at the meso scale， the characterization level of damage evolution models， and the computational accuracy of damage numerical simulations； improve the detection accuracy of damage identification testing at the macro scale， the accuracy of determination methods for damage thresholds， and the predictive ability of damage evolution models； further establishing a theoretical method system for cross-scale study of the propellant damage behaviors based on the developed standard specification for the study of damage behaviors for composite solid propellants in single-scale.
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Vol, 32, No.4, 2024
>分析与检测
>Calculation and Simulation
>Safety Performance and Assess
>Reviews
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Eco-friendly technology
2021-2022 Collection
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Initiating explosive device technology
2021-2022 Collection
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Damage and ignition
2021-2022 Collection
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Thermal decomposition，safety performance and evaluation
2021-2022 Collection
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Preparation and performance—Characterization of molding materials
2021-2022 Collection
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Preparation and performance—Characterization of synthesis
2021-2022 Collection
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Preparation and performance—Study on synthesis and performance
2021-2022 Collection
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Explosion and damage
2021-2022 Collection
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Detonation physics of energetic materials
2021-2022 Collection
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High efficiency destruction technology
2021-2022 Collection
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Propulsion and projection—Propulsion Materials structure and activity relationship
2021-2022 Collection
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Propulsion and projection—Preparation and performance about propulsion materials
2021-2022 Collection
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Calculation and simulation—Material structure and response
2021-2022 Collection
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Calculation and simulation—Structural evolution of materials
2021-2022 Collection
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Calculation and simulation—Material performance prediction
2021-2022 Collection
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Damage and Ignition
2020
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Detonation Physics
2020
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Crystal and microscopic analysis
2020-2022 发表
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Chemical Propellant
2021-2022 Collection
Special Issue
Virtual Special Issue
CJCR
