CHINESE JOURNAL OF ENERGETIC MATERIALS
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    • Effect of Heating Rates on the Cook-off Response Characteristics of JEO Explosive

      Online: March 28,2024 DOI: 10.11943/CJEM2024010

      Abstract (10) HTML (124) PDF 2.17 M (23) Comment (0) Favorites

      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.

    • Synthesis and Charaterization of 3,5,7-Triamino[1,2,4]triazolo[4,3-a][1,3,5]triazine Pentazolate Salt

      Online: March 27,2024 DOI: 10.11943/CJEM2024028

      Abstract (26) HTML (128) PDF 3.17 M (34) Comment (0) Favorites

      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 compound 4 was calculated using atomization method, the detonation performance was predicted using EXPLO5, and sensitivity was tested using BAM testing method. The results show that compound 4 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.

    • Advances of Assembly and Performance of Energetic Materials

      Online: March 26,2024 DOI: 10.11943/CJEM2023269

      Abstract (22) HTML (198) PDF 3.60 M (49) Comment (0) Favorites

      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.

    • Inkjet Printing Molding and Properties of HMX-based O/W Type Suspension Ink

      Online: March 25,2024 DOI: 10.11943/CJEM2024040

      Abstract (23) HTML (92) PDF 2.13 M (29) Comment (0) Favorites

      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.

    • Preparation and Combustion Performances of Core-Shell Structured Al@Cu(BTC)/Fe(BTC) Nano-Thermite

      Online: March 22,2024 DOI: 10.11943/CJEM2023268

      Abstract (43) HTML (166) PDF 2.86 M (59) Comment (0) Favorites

      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).

    • The Correlation Between the Geometric Shape of Neutral Nitro Molecules and their Crystal Properties: a Statistical Study

      Online: March 18,2024 DOI: 10.11943/CJEM2023263

      Abstract (48) HTML (142) PDF 1.63 M (117) Comment (0) Favorites

      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.

    • Transfer Characteristics of Explosion Energy Released by the Charge Confined to Tubes of Different Materials with Lateral Annular Slits

      Online: March 12,2024 DOI: 10.11943/CJEM2023266

      Abstract (60) HTML (72) PDF 2.57 M (121) Comment (0) Favorites

      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).

    • Thermal Erosion Characteristics and Variation Law of Triple Base Propellant

      Online: March 07,2024 DOI: 10.11943/CJEM2024033

      Abstract (71) HTML (28) PDF 897.79 K (192) Comment (0) Favorites

      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.

    • Multiscale Research Progress on Damage Behavior of Composite Solid Propellants

      Online: March 02,2024 DOI: 10.11943/CJEM2024014

      Abstract (88) HTML (124) PDF 4.69 M (168) Comment (0) Favorites

      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 ability of damage observation 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.

    • Synthesis and Performance Adjustments of 5-amino-2H-pyrazol-3,4-dione-3-oxime-4-hydrazone and Its Energetic Salts

      Online: February 29,2024 DOI: 10.11943/CJEM2023270

      Abstract (94) HTML (100) PDF 889.16 K (223) Comment (0) Favorites

      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 of 3 and 4 were obtained by solvent evaporation method and the crystals were characterized by single crystal X-ray diffraction. The structures of energetic compounds 3-6 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 that 3 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 of 4 (8499 m·s-1 and 30.2 GPa) higher than 3 (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 of 3, 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.

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