Abstract:

Abstract:A novel cage-like energetic compound， 4，4，8，8-tetranitro-2，6-dioxaadamantane， was synthesized via four steps involving oxidative cyclization， oxidation， oximation and gem-dinitration by using 9-oxabicyclo［3.3.1］nona-2，6-diene as raw material. Its structure was characterized by nuclear magnetic resonance（NMR）， Fourier transform infrared spectroscopy （FT‐IR） and elemental analysis （EA）， and single crystal X-ray diffraction （SC-XRD）was adopted to further confirm its crystal structure. The thermal stability was investigated by differential scanning calorimetry‐thermogravimetry（DSC‐TG）analysis， and detonation parameters were predicted by EXPLO5. Results show that 4，4，8，8-tetranitro-2，6-dioxaadamantane has a crystal density of 1.75 g·cm^-3 and belongs to monoclinic system， space groups P2₁/c. Its thermal decomposition temperature is 190.6 ℃， theoretical detonation velocity is 7705 m·s^-1， and detonation pressure is 25.75 GPa.

Abstract:Energetic potassium 3，8-dinitro（pyrazolo［5，1-c］［1，2，4］triazin-4-yl）nitramide （4） with a 3-dimensional metal-organic framework （3D EMOF） was synthesized via diazotization， cycloaddition and nitration by using 5-aminopyrazole （1） as raw material. Compound 4 was characterized and analyzed by nuclear magnetic resonance （NMR）， Fourier infrared spectroscopy （FT-IR）， mass spectrometry （MS）， single crystal X-ray diffraction （SC-XRD）， and differential scanning calorimetry （DSC）. The friction sensitivity and impact sensitivity of compound 4 were tested according to BAM standard. The detonation performance of compound 4 was predicted by EXPLO 5 software based on isodesmic reaction. Results show that the crystal of compound 4 belongs to monoclinic system， space groups P2₁/c， exhibits a 3-dimensional metal-organic framework （MOF） structure with a density of 2.021 g·cm^-3 at 150 K. Compound 4 has a thermal decomposition temperature of 203.4 ℃， a theoretical detonation velocity of 8717 m·s^-1， a theoretical detonation pressure of 33.5 GPa， a friction sensitivity of 168 N， and an impact sensitivity of <3 J.

Abstract:As an emerging high-energy substance， the development of perovskite energetic materials in both variety and quantity has more urgency. The first perchlorate-based double perovskite energetic material ｛（C₆H₁₄N₂）₂［Na（NH₄）（ClO₄）₆］｝_n （DPE-1） and a single perovskite energetic material ［（C₄H₁₂N₂）K（ClO₄）₃］_n （PAP-2） were synthesized by a solution-based method. The chemical structure， thermal stability， detonation performance， and mechanical sensitivity of both DPE-1 and PAP-2 were systematically investigated. Single-crystal X-ray diffraction analysis shows that DPE-1 crystallizes in a double perovskite structure with space group Pa-3， while PAP-2 crystallizes in a single perovskite structure with space group Pnma. Compared with the previously reported periodate-based double perovskite energetic material （C₆H₁₄N₂）₂［Na（NH₄）（IO₄）₆］｝_n（DPPE-1）， DPE-1 exhibits significant improvements in the thermal decomposition temperature （T_dec=368.9 ℃）， detonation velocity （D=8858 m·s^-1）， detonation pressure （p=38.4 GPa）， impact sensitivity （IS >40 J）， and friction sensitivity （FS=20 N）. These results validate the feasibility of exploring high-performance， green primary explosives within the double perovskite structural framework. PAP-2 demonstrates comparable thermal stability （T_dec>280 ℃） and detonation performance （D >8500 m·s^-1， p >30 GPa） with other single perovskite energetic materials in the same series， but its impact sensitivity is significantly increased and friction sensitivity is significantly reduced.

Abstract:Boron powder is often used as a combustible agent in energetic materials due to its high calorific value， volume calorific value and clean combustion products. However， the surface oxide layer of boron powder makes it difficult to ignite and brings low combustion efficiency. In order to improve the ignition and combustion performances， boron powder was wetly milled in hot acetonitrile to remove the surface oxide layer for obtaining pre-treated boron powder with high activity， according to the good solubility of boron oxide in acetonitrile solvent. Acetonitrile and n-hexane were used as a dual control agent， and then the pretreated boron powder and highly active aluminum were performed a secondary ball milling to finally prepare the boron-aluminum composite powder with surface-activated boron. The morphological characteristics， thermogravimetric， ignition and combustion characteristics of boron and composite powder were studied. The results showed that the content of surface boron oxide of boron powder was reduced after pretreatment with acetonitrile， pretreatment boron powder was easier to react with oxygen when heated in air， and the percentage of mass increase was 25.6% more than that of untreated boron powder. After pretreatment with hot acetonitrile， the surface boron oxide content decreased， the active boron content increased， and the ignition and combustion performances were significantly improved. The mass of composite powder with boron-aluminum mass ratio of 60/40 increased by 93% when heated in air， the ignition temperature was 738.1 ℃ at low heating rate， and the particle combustion time was 11.2 ms.

Abstract:To elucidate the effect of polyvinylidene fluoride （PVDF） content on the combustion performances of aluminum-based solid propellants， Al@PVDF composite powders with coating contents ranging from 2% to 14% were prepared via the solvent and non-solvent method. The thermal reactivity of Al@PVDF composite powders and the energy release and combustion performances of the corresponding solid propellants were analyzed using thermogravimetric-differential scanning calorimetry， constant volume combustion tests， and simultaneous ignition experiments. Results indicate that the PVDF coating significantly enhances the thermal reactivity of aluminum. At the 6% PVDF coating content， the aluminum powder achieves the maximum thermal weight gain and exothermic enthalpy value of 78.96% and 16.14 kJ·g^-1， respectively. As the PVDF content increases， the energy release of solid propellants exhibits a trend of initial increase， following by a decrease， subsequent re-increase， and final decline， and reaching the maximum heat release of 6026 J·g^-1 and pressurization of 4.45 MPa at 10% coating content. The ignition delay time of aluminum-oxygen reaction decreases from 53 ms to 12 ms. The pressure exponent of burning rate underwent a three-stage evolution， declining from 0.43 to 0.36， and further to 0.26. Analysis of condensed combustion products （CCPs） reveals a stage-dependent mechanism of PVDF content on combustion performances： the low coating content （2%-4%） inhibits molten aluminum agglomeration via pyrolysis products； the medium content （6%-8%） accelerates particle fragmentation and ignition but induces secondary agglomeration； the high content （10%-14%） generates excessive pyrolysis products that promote secondary fragmentation of agglomerates in gas-phase region.

Abstract:Boron （B）-based composite energetic materials， renowned for their high energy density， are employed in explosives and propellant formulations. In this study， B/ammonium perchlorate （AP）/polyvinylidene fluoride （PVDF） composite energetic microspheres were synthesized using an emulsion-solvent evaporation method， with different PVDF mass fractions （5%， 10%， 15%， and 20%）. The surface morphology of the prepared microspheres was characterized via scanning electron microscopy （SEM）. To evaluate their combustion behavior， a suspension combustion test was performed using an ultrasonic levitation laser ignition system. Through real-time diagnostics of micro-explosive combustion phenomena， the optimal PVDF content for the enhanced combustion performance was determined. The results revealed that the prepared microspheres possessed a near-spherical morphology and exhibited a three-stage combustion process （developing combustion stage， stable combustion stage and decreasing combustion stage）， which was also accompanied by micro-explosions. Among the formulations， the microspheres with 10% PVDF demonstrated the most favorable combustion characteristics， exhibiting the largest flame area and brightness， the highest BO₂ emission intensity （11291.8 counts）， the greatest BO₂ peak area integration （12856.8）， and the highest surface combustion temperature （1243.8 ℃）. These results indicate that the B/AP/PVDF microspheres exhibit optimal combustion characteristics and energy release performance at a PVDF content of 10%.

Abstract:To explore the application of in-situ spectroscopy for monitoring the curing reaction of energetic materials by using toluene diisocyanate （TDI） as curing agent， both In-situ Raman and infrared （IR） spectroscopy were employed to study the spectral changes before and after the curing reaction of 3，3-bis（azidomethyl）oxetane-tetrahydrofuran co-polyether （PBT）-TDI system. The Raman bands suitable for quantitative monitoring of the curing process were analyzed， and the results were evaluated. The vibrational modes of the Raman bands of reactants and products were identified using the density functional theory （DFT） method. The correlation between the curing reaction results obtained from IR and Raman spectroscopy was also discussed. Results show that the peak of 1534 cm^-1 in Raman spectroscopy of the PBT-TDI system exhibits a low signal-to-noise ratio， making it unsuitable for quantitative analysis. The reaction degree calculated from the peak of 1743 cm^-1 in Raman spectroscopy is significantly higher than that derived from the peak of 2269 cm^-1 in IR spectroscopy. The peak of 1505 cm^-1 in Raman spectroscopy is associated with the stretching vibration of the isocyanate （NCO） group. The difference in the degree of reaction between Raman and IR is due to the number of individual NCO groups in the TDI molecules that participate in the reaction. The two methods play complementary roles in monitoring the curing process.

Abstract:A testing device for measuring the curing shrinkage rate of solid propellants was developed in this study. In addition， the online monitoring test of curing shrinkage of HTPB/IPDI propellant was carried out. The relationship between curing shrinkage and time during the curing process of solid propellant was obtained. By constructing the relationship between curing shrinkage， curing degree and curing kinetics， the curing degree change law and curing kinetics model of solid propellant during curing process were obtained. The results show that the curing shrinkage of solid propellants changes in a three-stage S-type. The maximum curing shrinkage is about 0.108%， and the maximum curing reaction rate is 7.809×10^-6. During the isothermal curing process， the curing reaction rate curve of HTPB/IPDI propellant shows a bell-shaped curve， so the thermal curing of solid propellant has autocatalytic characteristics. The pre-exponential factor A₀ of the self-catalytic kinetics model for HTPB/IPDI propellant is 379.087 s^-1. The reaction orders m and n are 0.711 and 1.501. The results provide a new method to test the shrinkage of propellant and clarify the curing reaction characteristics of composite solid propellants.

Abstract:Ultrafine hexanitrostilbene （HNS） is widely used in explosion foil initiators and related applications due to its outstanding thermal stability and excellent high-voltage short-pulse performance. However， its high surface energy during service process leads to solid-phase ripening. Previous studies have explored the effects of temperature， residual solvents， and time on the solid-phase ripening of ultrafine HNS， but these investigations primarily focused on isolated or narrowly factors. Currently， no multivariate predictive model has been established. In this study， a predictive model was developed based on previously obtained small angle X-ray scattering （SAXS） data， including specific surface area （SSA） and relative specific surface area （RSSA）， obtained under varying temperatures and residual dimethylformamide （DMF） contents. The model was constructed using machine learning algorithms and optimized empirical models. It comprehensively accounts for time， temperature， and residual DMF content in its predictions. The results show that on the training dataset， the random forest （RF） model achieved an R² of 0.9989 in predictions， while the polynomial regression （PR） model and optimized empirical model attained R² values of 0.9091 and 0.9129， respectively. By comparing the prediction performance of these three models， the most suitable model for predicting the solid-phase ripening process of ultrafine HNS was identified. Furthermore， purity tests and scanning electron microscopy （SEM） characterization revealed that particle characteristic variations exert significantly influence on the extent of solid-phase ripening in ultrafine HNS. A predictive method was established for the solid-phase ripening process of ultrafine HNS， laying a foundation for investigating its aging mechanisms and optimizing storage stability.

Abstract:In order to investigate the influencing factors of the pressing effect and safety of the irregular-shaped charges， numerical simulation of the pressing process of the irregular-shaped JH-2 charge， with a diameter of D=88 mm， a molding height of H=132 mm， and a wedge angle of α=60°， was carried out by using the dynamics of continuous media method in the Marc finite element software， and the effects of process parameters such as pressing pressure， pressing rate， initial relative density， friction coefficient， and holding time on the forming of the charges， including the molding density and internal stress， were studied systematically. The results show that the density and stress distributions inside the irregular-shaped charge are nonuniform， and there are obvious regions of density loose and stress concentration. The pressing pressure， initial relative density， holding time and friction coefficient affect the molding density and stress distribution of charges simultaneously， while the pressing pressure， initial relative density and pressing rate are the main factors affecting the stress concentration of the irregular-shaped charge. In view of this irregular-shaped structure， when the pressing pressure is 300-350 MPa， pressing rate is 1.5 mm·s^-1， initial relative density is 0.65， friction coefficient is 0.15， and holding time is 120 s， the density distribution of the irregular-shaped charge is relatively uniform， and the stress gradient difference is small， which can improve the molding quality， reduce the stress concentration and avoid cracks， and ensure the charging safety.

Abstract:To accurately analyze the interior ballistic performance and launch overload of image terminal guided projectiles， the connotative essence of the firing with different charge numbers was investigated based on the characteristics and working principles of the adaptive launch platform and launch charge. The interior ballistic two-phase flow model for image terminal guided projectile was established， and its rationality was verified through simulations and measured data under two different working conditions. Building on this， the evolution laws of pressure fluctuation and projectile motion in the bore of a certain type of image terminal guided projectile with different charge numbers were analyzed using the verified interior ballistic two-phase flow model. Furthermore， the launch overload characteristics of this type of image terminal guided projectile with different charge numbers were studied through the established engineering calculation model of launch overload. The results show that the relative errors of the maximum pressure at the bottom of the bore and the initial velocity of the projectile between two verification conditions are less than 2%， and the variation laws of the pressure at the bottom of the bore and the pressure wave in the bore with time are highly consistent between simulation and measurement. The internal ballistic performance and launch overload variation laws of the image terminal guided projectile with different charges obtained from the verified model are consistent with the general laws of the actual launching process.

Abstract:According to the connection mode of molecules and whether the molecule is neutral， the high-energy heat-resistant compounds reported in recent years are divided into three categories： fused ring， linked heterocyclic and ionic. The structural characteristics， synthesis methods， physicochemical properties and detonation performances of three kinds of high-energy heat-resistant compounds are reviewed. and the application prospects are evaluated. The development direction of the synthesis of high-energy heat-resistant compound is prospected： developing universal construction technology of skeleton， promoting the integration of computational simulation and molecular design， and innovating green and efficient synthesis process. It provides a reference for the design and synthesis of new high-energy heat-resistant compounds.

Abstract:Technological and industrial transformations driven by data science and artificial intelligence are profoundly impacting the field of materials science， presenting both unprecedented opportunities and significant challenges for the innovation of energetic materials. As an emerging technology， machine learning offers novel research paradigm for the molecular design and synthesis of energetic materials. It is expected to solve the long-standing bottlenecks such as low efficiency， high cost， and lengthy development cycles. Although some successful cases have been reported， the application of machine learning across the full research cycle of energetic molecules—design， screening， synthesis， and performance validation—remains in a relatively immature stage compared with the application in other advanced materials domains. This review outlines the current research status of machine learning-assisted development of energetic materials， summarizes its applications in molecular design， single-property prediction， and multi-property simultaneous prediction. Nonetheless， the use of machine learning in design and synthesis of energetic materials with targeted properties remains fraught with challenges. Future efforts should prioritize the control of data quality and the construction of standardization frameworks， the development of interpretable machine learning models， and the establishment of interdisciplinary integration platforms， further promoting the efficient creation of high-performance energetic materials.