Abstract:Hyphenated techniques of thermal analysis， including common thermogravimetric-differential scanning calorimetry （TG-DSC）， thermogravimetric-infrared/mass spectrometry （TG-FTIR/MS）， Fourier transform infrared spectroscopy/solid-state in situ reaction techniques （Thermolysis/RSFTIR） and thermogravimetric-infrared-mass spectrometry （TG-FTIR-MS）， are effective ways to study the thermal decomposition properties and mechanisms of energetic materials. Compared to the single thermal analysis techniques， the hyphenated techniques of thermal analysis are more adequate， efficient and comprehensive ways to evaluate the thermal behaviors and thermal stability and to reveal the thermal decomposition mechanism of energetic materials. A comprehensive and in-depth study of the physicochemical properties of energetic materials by hyphenated techniques of thermal analysis is of great practical significance and value in improving and enhancing the performance of energetic materials in applications. Herein， this paper presents a comprehensive review of the advance in the application of TG-DSC， TG-MS， TG-FTIR-MS， TG-FTIR-GC-MS and Thermolysis/RSFTIR hyphenated techniques in the study of energetic materials. The research contents， important results， features and advantages of these techniques are analyzed， and related perspectives are presented， such as developing high-performance computational analysis software， solving the problems such as the deconvolution of overlapping mass spectral peaks in mass spectral analysis， and introducing a new extension system in the thermal analyzer to expand the scope of their application， thus providing technical support for the thermal analysis of new energetic materials.

Abstract:To search green， low-toxicity lead-free primary explosive， a new tetrazole derivative ligand 1H-5-acylhydrazide tetrazole （TZCA） and its complex Ni（TZCA）₂（ClO₄）₂ （ECCs-1） were synthesized by hydrazinolysis and coordination reactions using ethyl 1H-tetrazole-5-carboxylate as the raw material. The molecular structure and thermal decomposition properties of the title complex were tested by X-ray single crystal diffraction， IR diffraction， NMR， elemental analysis， thermogravimetric and simultaneous thermal analyzers. The heat of combustion of ECCs-1 was tested by oxygen bomb calorimetry and its energy parameters were predicted based on Hess law and K-J equation. Sensitivities of ECCs-1 were tested by BAM test methods. The results show that the density of TZCA is 1.83 g·cm^-3， monoclinic crystal system， C2/c space group， the stacking mode is V-staggered stacking. The density of ECCs-1 powder is 1.90 g·cm^-3， impact sensitivity is 17 J， friction sensitivity is 72 N， thermal decomposition temperature is 336 ℃， activation energy of the thermal decomposition reaction is 183.3 kJ·mol^-1， thermal explosion critical temperature is 309.8 ℃， activation entropy is 46.745 J·K^-1·mol^-1， and the activation enthalpy is 178.563 kJ·mol^-1. The hot baking and lead plate tests both show that ECCs-1 has a good detonation performance.

Abstract:In order to obtain super thermite with spherical core-shell structure for 3D printing of energetic materials， Al_2#@CuO and Al_2#@Bi₂O₃ super thermites possessing highly spherical core-shell structure were prepared by spray granulation method for directly coating solid particles. The influence of construction parameters （particle size ratio and solid content） on particle size of super thermite was studied by using NanoMeasure statistical software. The spherical core-shell structure was characterized by scanning electron microscopy and X-ray diffraction. The flowability of super thermite was characterized using the angle of repose method. The ignition characteristics were observed using high-speed cameras. The results show that two types of super thermite possessing highly spherical core-shell structure were prepared using construction parameters of solid content 25%， 2# aluminum powder， and nano metal oxide （CuO， Bi₂O₃） particle size. The structure was an ideal spherical core-shell structure， with an average particle size of about 40 μm. The average thickness of the shell is 7.79 μm （Al_2#@CuO-25%）， 10.47 μm（Al_2#@Bi₂O₃-25%）. Compared with the mechanically mixed sample， the flowability of super thermite with spherical core-shell structure displays a great improvement. The angle of repose of Al/CuO system reduces from 48.8° to 22.9°， and the angle of repose of Al/Bi₂O₃ system decreases from 37.3° to 16.6°. The combustion time of Al_2#@CuO super thermite with spherical core-shell structure increases from 100 ms to about 0.9 s， indicating that microstructure variation has an impact on its combustion characteristics.

Abstract:Quantitative characterization of its physical structure is crucial for regulating and enhancing the performance of PBX. Utilizing micro-CT， image processing， and statistical analysis， we researched the quantitative acquisition of characteristic parameters for molding granules. We conducted research on image processing and statistical analysis to quantitatively obtain the characteristic parameters of molding granules based on micro-CT. The characteristic parameters of TATB-based molding granules were characterized by this method， and an evaluation of the characterization method was conducted. The results suggest that this method can implement the quantitative characterization of the size， morphology， porosity， density， and packing characteristics of the molding granules. The granule size and sphericity of the TATB-based molding granules approximately follow the exponential Gaussian and Weibull distributions， respectively. The intrinsic density is 1.35 g·cm^-3， with a visible porosity of 2.3%（@spatial resolution 14.3 μm）， and a volume fraction of 0.69. Evaluation experiments demonstrate that the method exhibits good accuracy， stability， and repeatability. The characterization results of granule size are consistent with those of the sieving process， and the relative deviation of the characterization results of main characteristic parameters in different periods is less than 1%. The results of morphology and properties are relatively significantly influenced by the packing state of granules and the spatial resolution of micro-CT.

Abstract:The cylinder test is one of the most commonly used tests to calibrate the parameters of the equation of state for explosive detonation products. A probe cylinder test platform was designed and established in order to determine the parameters of the JWL equation of state for explosive detonation products. A 20 ns high-resolution pulse chronograph and a set of probes with radial displacement differences were used to record multiple discrete points during the expansion process of the cylinder. When the cylinder expands to the head of the probe to form a circuit loop， the pulse chronometer records the time. Based on this， the displacement-time history curve of the cylinder wall can be obtained. Two probe cylinder tests of TNT explosives were carried out， and discrete points of cylinder expansion displacement were obtained. The experimental results show that the difference between the two sets of test curves is small， indicating that the probe cylinder test has good repeatability. The JWL equation of state parameters of TNT explosive detonation products were determined using the BP-GA algorithm. The determined JWL parameters were then substituted into the finite element software for numerical verification， and the results showed that the determination coefficient R² of the simulation displacement curve was 0.9997， indicating the high accuracy of JWL parameters.

Abstract:Using droplet microfluidics technology， an aqueous solution of the active agent at a concentration of 0.5% was used as the continuous phase， and an ethyl acetate solution of DAAF was employed as the dispersed phase. DAAF/F2602 composite microspheres were prepared by fluid-focused microchanneling. The effects of two-phase flow rate ratio， concentration of dispersed phase， and type of active agent on particle morphology， particle size， and roundness of DAAF/F2602 composite microspheres were investigated. The optimal process conditions， including a suspension concentration of 4%， a two-phase flow rate ratio of 16∶1 and an active agent of CTAB， were obtained and compared with the aqueous suspension method. The results show that the DAAF crystalline shape of the samples obtained from two preparation methods are unchanged， the impact sensitivity is higher than 100 J， and the friction sensitivity is 0% and the friction sensibility are more than 360 N， indicating that the two samples have good safety performance. Among them， the particle sizes of DAAF/F2602 composite microspheres which obtained by the droplet microfluidization method were in the range of 20.22 to 53.85 μm， which were smaller than that obtained by the aqueous suspension method （121-356 μm）.Furthermore， the particle sizes distribution was observed to be more uniform. Thethermal decomposition exhibited a delayed peak temperature by 6.45 ℃， and the activation energy was increased by 6.12 kJ·mol^-1， which lead to improved thermal stability. The cone angle generated by the stacking of DAAF/F2602 composite microspheres which obtained by the droplet microfluidization method， is 34°. This angle is smaller than that of composite particles obtained by the water suspension method （40°）， which indicate better dispersion property.

Abstract:In order to obtain spherical granulations with regular shape， good dispersibility and uniform particle size， the effects of different binders on 2，2"，4，4"，6，6"-hexanitrodiphenylethylene （HNS） composite microspheres were studied by using droplet microfluidic technology. Fluoroelastomer （F₂₆₀₄）， nitrocellulose （NC） and glycidyl azide polymer （GAP） were selected to prepare spherical granulation of submicron HNS， and submicron-level HNS/F₂₆₀₄ （95/5）， HNS/NC （95/5） and HNS/GAP （95/5） composite microspheres were successfully prepared. Resultant microspheres were characterized by scanning electron microscope， X-ray diffractometer， specific surface area， thermal analyzer， true density tester and mechanical sensitivity tester. Results indicated that such methods could obtain the HNS composite microspheres with high sphericity， monodisperse， narrow size distribution， good roundness and improved safety performances. The average circularities were 0.934， 0.915 and 0.925 with D₅₀ of 45.39， 58.68 μm and 45.43 μm （the span was less than 0.55）， respectively. Thermal decomposition peak temperatures were 354.44， 349.53 ℃ and 339.37 ℃ for HNS/F₂₆₀₄， HNS/NC and HNS/GAP， respectively. The spheroidization process increases the true density of the microspheres to 1.9408， 1.9383 g·cm^-3 and 1.9204 g·cm^-3， respectively， which can effectively improve the HNS charge performance. The cone angles of 27°， 24.3°， and 24° indicated that microspheres have good dispersion performances. Compared with submicron HNS， the impact sensitivity of the three microspheres was increased by 5.5， 4， 3.5 J， and the friction sensitivity was increased by 52， 36 N and 4 N， respectively， indicating a better safety performance.

Abstract:The safety issues of weapons and ammunition are essential that they matter the survivability and effectiveness of weaponry. The complex and harsh enviroments faced by ammunition lead to the high requirment of ammunition safety that the development of safe ammunition is the only way. Ammunition safety mainly depends on inherent safety and safety enhancement technology. Using insensitive explosives is the key way to improve the inherent safety of ammunition， while the enhancement and protection of charge and structure are important means to improve ammunition safety . In order to meet the requirements of high damage power and safety of ammunition， it is necessary to balance and coordinate the prominent contradiction between high energy and insensitivity of explosives from the multi-scale structures， such as molecules， crystals and mixed systems of explosives. Safety enhancement technologies such as charge structures， weak link structurse of projectiles and protection enhancements can effectively control the accidental ignition， reaction violence and evolution ammunition charges， and furthermore improve the safety of ammunition under abnormal environment and accident conditions. Therefore， the design ideas and technicalapproches for safety ammunition systems were proposed， including strengthening the foundation of multi-scale material design and performance control of insensitive explosives， complementing the shortcomings of charge structures， protection enhancement， and accidental ignition and reaction control， and exploring and developing the integrated design of material，- structure- and function .

Abstract:In order to investigate the shock initiation of warhead charge by multiple explosively formed projectiles （MEFP） impacts， the shock initiation experiments of covered Composition B by single EFP and dual EFP were conducted to test the shock initiation capacity of single EFP and dual EFP on covered Composition B. Moreover， the numerical simulations on shock initiation of covered Composition B by EFP were carried out by AUTODYN finite-element software， the formation processes of single EFP and dual EFP and their shock initiation processes of covered Composition B， were analyzed respectively， and the critical cover plate thickness （H_c） for the detonation of Composition B was obtained. Further， an engineering calculation model of the critical initiation condition of covered charge with dual EFP was established. The experimental results show that the length of EFP is 18 mm and the diameter is 19 mm. The critical cover plate thickness range is 10 mm≤H_c<15 mm for shock initiation of covered Composition B by single EFP impact， while the critical initiation cover plate thickness range is 15 mm≤H_c<20 mm for dual EFP impacts. Besides， the numerical simulation results show that the critical cover plate thickness is 13 mm for shock initiation of covered composition B by single EFP. While for the action of double EFP， the critical initiation cover plate thickness is 19 mm， which is 46.2% higher than that for single EFP. The numerical simulation results are consistent with experimental results. Finally， the calculation model can provide a good prediction of the critical initiation condition of the covered charge with dual EFP.

Abstract:To study the jet formation and failure characteristics of penetrating concrete and rock targets of shaped charge with large barrier， the jet formation by using X-ray cinematography and static armor-piercing into concrete and rock targets were carried out. Meanwhile， the evolution process of detonation wave， the rod jet formation of shaped charge with large barrier and penetration process of concrete and rock targets are simulated by ANSYS/AUTODYN software. Combined with the experimental results， the penetration damage characteristics of the shaped charge rod jet to concrete and rock targets were analyzed. Results show that the Lee-Tarver equation of state can accurately describe the propagation process of the internal detonation wave， and the maximum error of forming jet parameters （projectile length， jet length， jet head velocity and jet diameter） is 12.8% compared with the test. The continuous rod-like jet with large aspect ratio can be formed after detonation of the shaped charge with large barrier. There are obvious craters in the penetrated concrete and rock targets， and the jet has no obvious reaming effect during the penetrating concrete process. The penetration depth and hole diameter of the penetrated concrete target are 46.7% and 48.1% larger than those of rock target in the test. However， the surface of the rock target is seriously damaged and the crater area is larger. Compared with the concrete target， cracks in rock target are continuously generated and developed significantly in the process of jet penetrating and the length and width of cracks formed are larger than those of concrete targets. The damage range around the rock target penetration channel is larger， and the internal damage of the target is serious.