Abstract:In order to accurately understand the mechanical characteristic of 1，3，5-triamino-2，4，6-trinitrobenzene （TATB）-based polymer bonded explosive （PBX） under compressive loading， an in-situ measurement technique based on micro X-ray computed tomography （μ-CT） imaging and digital volume correlation （DVC） was proposed. The in-situ scanning for TATB based PBX sample under uniaxial compression was carried out by using μ-CT and the three-dimensional digital volume images of the samples under different loading were obtained. Then， two sets of digital volume images obtained before and after loading respectively were analyzed by using local DVC method based on the Inverse Compositional Gauss-Newton （IC-GN） algorithm and the three-dimensional internal displacement and strain fields with sub-voxel accuracy were obtained. The internal stress fields were finally rebuilt according to the elastic Hook’s rule. The results show that the generation and development process of the strain localization zone inside the sample could be directly revealed based on the internal measurement technique combining DVC and μ-CT. In addition， the Zero-mean Normalized Cross-Correlation （ZNCC） coefficients are commonly lower at the microcracks. In practical applications， the location of sub-voxel microcracks could be identified by the distribution of ZNCC coefficients.

Abstract:In order to explore the effects of structure on combustion performance of aluminum/polytetrafluoroethylene （Al/PTFE）-based reactive materials and improve combustion performance of fluorine-based thermite， additive manufacturing technology （3D printing） was utilized to prepare Al/PTFE-based reactive materials with solid， hollow， core-shell， and confined hollow structures， as well as Al/CuO-based and Al/Fe₂O₃-based reactive materials with confined hollow structures. The microstructure， thermal performance， combustion rate， and gas production performance were assessed by scanning electron microscope （SEM）， differential scanning calorimetry （DSC）， high speed camera， and constant volume combustion chamber. The results show that each sample exhibits intact structure and uniform components. Under the circumstance of same mass， the samples with core-shell and confined hollow structures display lower heat release than that of samples with solid and hollow structures. The burning rate of samples with hollow， core-shell， and confined hollow structures is 1.44， 1.32， and 2.62 times higher than that of samples with solid structure， respectively. Obvious improvement in gas production performance and pressurization rate appears for samples with hollow and confined hollow structures， especially for samples with confined hollow structure. The burning rate of Al/PTFE， Al/CuO， and Al/Fe₂O₃ materials with confined hollow structure is significantly higher than that of corresponding samples with solid structure， particularly for Al/Fe₂O₃ materials. The approach to regulate combustion performance of lines by preparing materials with hollow structure is expected to provide a novel idea for designing new high-performance weapons.

Abstract:The structural integrity evaluation of the metal-explosive bonding interface is of great importance and engineering value. To realize high sensitivity detection of interfacial debonding defects in the metal-explosive structure， the ultrasonic detection and imaging methods based on multiple pulse-echoes was proposed. The acoustic impedance and reflection characteristics at bonding interface of aluminum， shellac， and RDX were calculated and analyzed. For specimens with different adhesive layer thickness and artificial prefabricated debonding defects， debonding information were extracted from the captured multiple echoes. The influence of adhesive layer with different thickness on the amplitude of multiple echoes was discussed and analyzed. Results show that dramatical amplitude difference exists in the reflected waves between the aluminum-adhesive and the aluminum-water interface. Both the first echo and multiple echoes could effectively distinguish the area with and without adhesive layer. The acoustic attenuation caused by the aluminum-adhesive interface keeps accumulating in high order echoes. As the thickness of the adhesive layer increases， the cumulative effect of the acoustic attenuation difference in the multiple ultrasonic echoes between aluminum-adhesive and aluminum-water interfaces gradually weakens. Experimental results show that the minimum debonding defects with Φ1.5 mm circular and 1 mm wide rectangular shape could be detected using multiple ultrasonic echoes method.

Abstract:（C₆H₁₄N₂）［Na（ClO₄）₃］ is a representative of energetic perovskite compounds. It is necessary to clarify the corresponding thermal decomposition behavior， thermal decomposition mechanism and sensitivity characteristics in order to promote the application in formulations. Thermal decomposition parameters， including heat release amount and decomposition temperatures， were obtained by simultaneous differential scanning calorimetric and thermogravimetric analyses methods. The relevant decomposition mechanism was analyzed by kinetic simulation calculations. The decomposition products and decomposition processes of （C₆H₁₄N₂）［Na（ClO₄）₃］ were explored by DSC/TG-FTIR-MS coupled technique combined with in-situ infrared technology. The parameters of thermal sensitivity， friction sensitivity and impact sensitivity were obtained by national military standard methods. The results show that the heat of decomposition of （C₆H₁₄N₂）［Na（ClO₄）₃］ is 4227 J·g^-1 at the heating rate of 10 ℃·min^-1 and the decomposition temperature reaches 345 ℃， which is higher than that of most active energetic materials， including Hexogen （RDX）， ogen （HMX） and hexanitrohexaazoisowuzane （CL-20）， indicating an outstanding thermal stability. The decomposition products analysis shows that the cubic cage-like skeleton effectively stabilizes the internal organic molecule， resulting in the high thermal stability of （C₆H₁₄N₂）［Na（ClO₄）₃］. In addition， the outgassing amount of （C₆H₁₄N₂）［Na（ClO₄）₃］ heated at 100 ℃ for 48 h is about 0.04 mL·g^-1， and the impact sensitivity and mechanical sensitivity are 32% and 80%， respectively， which are better than RDX and HMX.

Abstract:The particle size and morphology of energetic material crystal have a great influence on its performance. In order to study the relationship between crystal morphology， particle size and thermal decomposition performance of 1，1-diamino-2，2-dinitroethylene （FOX-7） explosive， FOX-7 explosive particles with different morphologies and particle sizes were prepared according to solvent/non-solvent method. Scanning electron microscope （SEM）， X-ray diffractometer （XRD）， differential scanning calorimeter （DSC） and impact sensitivity tester were used to investigate the crystal morphology and particle size， crystal form， thermal decomposition property and safety property of FOX-7 explosives， respectively. The results show that by changing the cooling rate， stirring rate and other process conditions， FOX-7 explosive particles with different morphologies such as sea urchin shape， spherical shape， flower shape and block shape can be obtained. The crystal form of prepared FOX-7 explosive is consistent with that of raw material as α-form. The crystal morphology and particle size of FOX-7 have a great influence on the breaking of intramolecular hydrogen bonds and the destruction of the conjugated system， and the spherical shape is beneficial to increase the thermal decomposition temperature. For the FOX-7 sample with a same shape， the larger the particle size， the better the thermal stability. Among the FOX-7 samples with diameters of tens of microns， the sample with spherical morphology has the best safety performance.

Abstract:In order to achieve the safety of the preparation process of ultrafine zirconium （Zr） powder， a method for preparing core-shell Zr powder by continuous flow at microscale was studied. A continuous microfluidic system consisting of microfluidic unit and spray-drying unit was established to verify the feasibility. The system can realize the microscale mixing of components， the formation of core-shell structure and the post-processing of samples continuously. Using Zr powder and nitrocellulose （NC） as composite components， the structure regulation of Zr@NC was studied by controlling content of NC and adjusting dry gas pressure at the microscale. In addition， the activity and safety of Zr@NC were analyzed by thermal analysis and electrostatic spark sensitivity test. The results show that the Zr powder with uniform morphology and core-shell structure can be prepared by the continuous microfluidic system. Thermal analysis results show that the oxidation weight gain of Zr@NC is only 1.04% lower than that of the raw Zr， and the energy release is faster. According to the electrostatic spark sensitivity test， it was found that the 50% ignition energy of Zr@NC is increased from 1.42 mJ to 197.82 mJ compared with the raw Zr， which means the electrostatic spark sensitivity is greatly reduced.

Abstract:The explosives and propellants containing hexanitrohexaazaisowurtzitane （CL-20） and aluminum （Al） powders show excellent energy properties， and Al/CL-20-based energetic materials have become the focus of research. By using polyvinylidene fluoride （PVDF） as binder combined with nano-aluminum （nAl） powders and CL-20， the nAl@PVDF and nAl@PVDF@CL-20 composite energetic particles could be prepared via microfluidic technology. The morphology， internal structure， and particle size of two composite particles were observed by scanning electron microscope （SEM） and laser particle size analyzer. Chemical structure of composite particles was analyzed by Fourier transform infrared spectrometer （FTIR）. Thermogravimetry-differential scanning calorimetry （TG-DSC） was used for thermal analysis. The results show that the as-prepared composite particles exhibit high sphericity， good dispersibility， and uniform particle size distribution with the particle size of 10-20 μm. The components of composite particles are well-distributed， and there is no chemical bond between the components. Thermal analysis results display that both nAl@PVDF and nAl@PVDF@CL-20 composite particles exhibit pre-ignition reaction between PVDF and surface oxidation layer of nAl. The heat released from the pre-ignition reaction could promote the decomposition of PVDF. The decomposition reaction of CL-20 could be accelerated by combining with nAl and PVDF. Compared with nAl/PVDF/CL-20 material acquired by mechanical mixing， nAl@PVDF@CL-20 composite particles prepared by microfluidic method possess homogeneous component distribution.

Abstract:Metastable intermolecular composites （MICs） have the advantages of ultra-high reaction rate， high bulk energy density and micron critical reaction propagation size. They show broad application prospects in military fields such as micro energetic devices and rocket propellants. Nano Al/CuO energetic composite films are one of the research hotspots in the field of metastable intermolecular composites. They are prepared by vapor deposition， compatible with the micromachining process of energetic micro electro mechanical systems （MEMS）， and have great application prospects in integrated energetic devices. The preparation， thermal properties， combustion properties， reaction kinetics， the effect of transition layer on the properties of Nano Al/CuO energetic composite films， energetic devices （igniters） and their application technology are reviewed， and the development direction of Nano Al/CuO energetic composite films is prospected.

Abstract:A cyclo-pentazolate anion-based energetic cocrystal （NH₃OH⁺N₅^-）₂·NH₃OH⁺Cl^-·H₂O was designed and synthesized by AgN₅ （or NH₃OH⁺N₅^-） and hydroxylamine hydrochloride（NH₃OH⁺Cl^-） as raw materials. The structure of the compound was characterized by X-ray single crystal diffraction， infrared spectroscopy and elemental analysis. The structure belongs to the monoclinic crystal system，the P2₁/n space group， a=3.8390（6）Å， b=14.665（2）Å， c=21.975（3）Å， V=1236.4（3）ų， α=γ=90°， β=92.034（3）°， Z=1， D_c=1.589 g·cm^-3. In addition， the thermal stability of （NH₃OH⁺N₅^-）₂·NH₃OH⁺Cl^-·H₂O was studied using DSC and TG， and the results showed that its initial decomposition temperature was about 95.6 ℃. Its detonation velocity and detonation pressure were calculated by EXPLO5 to be 8260 m·s^-1 and 23.79 GPa. （NH₃OH⁺N₅^-）₂·NH₃OH⁺Cl^-·H₂O has low impact and friction sensitivities （IS>40 J； FS>360 N）， as the cocrystal of hydroxylamine hydrochloride can greatly reduce the mechanical sensitivity of NH₃OH⁺N₅^-.

Abstract:In order to clarify the influence mechanism of H₂O and H₂O₂ molecules on the thermal stability of energetic cocrystals， molecular dynamics （MD） simulation method was employed to analyze the diffusion behavior and thermal decomposition mechanism of solvent molecules in α-CL-20 and CL-20/H₂O₂ （orthogonal/monoclinic）. The results show that both H₂O and H₂O₂ will diffuse out of the cell as the temperature rises， among which H₂O molecules diffuse faster； when the temperature is lower than 500 K， the monoclinic CL-20/H₂O₂ lattice framework has the ability to hinder the diffusion of H₂O₂ molecules. When the temperature rises above 500 K， this hindering effect no longer exists. In the process of thermal decomposition， α-CL-20 releases energy the slowest， and the decomposition of CL-20 also proceeds the slowest； when the temperature is lower than 1500 K， the solvent exhibits a certain stabilizing effect on the thermal decomposition of energetic components， but this effect disappears as the temperature rises. In addition， the presence of solvents can increase the lattice energy significantly.