Abstract:To develop novel active metal complex fuels， three new types of active metal complexes were synthesized using cyanoborohydride （CBH^-） as the anion， transition metal Cu（Ⅱ） as the central ion， and 1-methylimidazole （1-MIM）， 2-methylimidazole （2-MIM） and 4-methylimidazole （4-MIM） as ligands. Their structures were accurately characterized via infrared spectroscopy and single-crystal X-ray diffraction， and the corresponding structural formulas are ［Cu（1-MIM）₄］（CBH）₂， ［Cu（2-MIM）₄］（CBH）₂ and ［Cu（4-MIM）₄］（CBH）₂， respectively. The thermal decomposition properties， energy density and mechanical sensitivity of the three novel metal complexes were tested. Their theoretical specific impulse when combined with 90 % H₂O₂ oxidizer was calculated based on NASA-CEA， and the hypergolic ignition performance of the novel active metal complex fuels with 90% H₂O₂ was investigated via high-speed photography. The results show that all three metal complexes exhibit high energy density （26.5-27.3 kJ·g^-1） and low sensitivity， with friction sensitivity >360 N and impact sensitivity >40 J. All three complexes can undergo hypergolic reaction upon contact with 90 % H₂O₂ at room temperature， and the ignition activity follows the order ［Cu（2-MIM）₄］（CBH）₂ < ［Cu（4-MIM）₄］（CBH）₂ < ［Cu（1-MIM）₄］（CBH）₂. Among them， ［Cu（1-MIM）₄］（CBH）₂ has the shortest ignition delay time of 43 ms， indicating that different methyl substitution positions on the ligand significantly affect the hypergolic ignition performance of the complexes with 90% H₂O₂.

Abstract:4，4""，5，5""-Tetranitro-2，2""-biimidazole （TNBI）， as an energetic material with excellent overall performance， exhibits promising application potential. However， its significant hygroscopicity severely limits practical application， primarily due to the acidic hydrogen atoms in its molecular structure that readily form hydrogen bonding networks with water. To address this issue， the insensitive explosive 3-amino-4-（4，5-diamino-1，2，4-triazol-3-yl）furazan （TATF） was employed to replace the hydrogen bonding network between TNBI and water molecules， forming a TNBI-TATF energetic ionic salt. The structure and properties of the new compound were characterized by hygroscopicity experiments， nuclear magnetic resonance （NMR）， Fourier transform infrared spectroscopy （FTIR）， simultaneous thermogravimetric analysis-differential scanning calorimetry （TGA-DSC）， and single-crystal X-ray diffractometry. Results show that TNBI²⁻ and TATF⁺ form a dense and highly directional hydrogen bonding network， guiding the crystal to adopt a layered packing arrangement. This layered structure buffers and absorbs external mechanical impact through a “slip” mechanism， thereby reducing mechanical sensitivity. Consequently， TNBI-TATF possesses both favorable detonation performance and stability.

Abstract:Starting from 3，5-dichloroanisole， 2，4，6-trinitro-3，5-dichloroanisole was obtained via nitration with mixed acid， which was then reacted with 4-aminopyrazole to afford 3-chloro-5-methoxy-2，4，6-trinitro-N-（1H-pyrazol-4-yl）aniline （1）. Subsequent nitration of compound 1 with fuming nitric acid followed by amination with aqueous ammonia successfully yielded N-（3，5-diamino-2，4，6-trinitrophenyl）-3，5-dinitro-1H-pyrazol-4-amine （4）. The structures of the target compounds were characterized by fourier transform infrared spectroscopy， nuclear magnetic resonance， elemental analysis and single-crystal X-ray diffraction. The detonation properties were calculated using the EXPLO5 software. A simultaneous thermogravimetry-differential scanning calorimetry analyzer and impact/friction sensitivity testers were employed to determine the thermal decomposition temperature and mechanical sensitivities， respectively. The results show that compound 4 crystallizes in the monoclinic crystal system with the P2₁ space group. Its unit cell parameters are a=6.2175（2） Å， b=9.2348（4） Å， c=12.5837（5） Å， giving a density of 1.91 g·cm^-3 （170 K）. The theoretical detonation velocity and detonation pressure are 8576 m·s^-1 and 32.1 GPa， respectively. Its thermal decomposition temperature is 217 ℃； the impact sensitivity is 15 J and the friction sensitivity is 160 N. Compound 4 exhibits favorable detonation performance and thermal stability.

Abstract:3，4-Dinitropyrazole （DNP） has a moderate melting point， high density， and excellent detonation performance， and is regarded as a promising carrier explosive for melt-cast formulations. However， DNP exhibits a certain degree of hygroscopicity under high-temperature and high-humidity conditions， which may adversely affect charge-processing operations and the final performance of explosive products. The hygroscopic behavior of DNP powder was investigated using the desiccator equilibrium method. The effects of post-treatment method， temperature， relative humidity， and particle size on moisture sorption were evaluated. The influence of moisture uptake on the thermal decomposition behavior of DNP was further examined， and quantum chemical calculations were performed to predict its key moisture-sorption sites. The results showed that the post-treatment method had the most significant effect on the hygroscopicity of DNP， with benzene-recrystallized DNP exhibiting the lowest moisture sorption. Temperature and relative humidity had secondary effects， and the hygroscopicity of DNP increased with increasing temperature and relative humidity， whereas particle size had only a minor influence. When the ambient temperature was below 30 ℃， the critical relative humidity of DNP was higher than 84%， whereas it decreased to 75% at 40 ℃. Under the corresponding critical relative humidity conditions， the equilibrium moisture content of benzene-recrystallized DNP remained below 0.31%， with no obvious agglomeration or caking. Moreover， no significant changes were observed in the melting point or thermal decomposition temperature of DNP after moisture sorption. These results indicate that the hygroscopicity of DNP powder can be reduced through appropriate post-treatment and that moisture-related problems can be effectively prevented by controlling the environmental temperature and relative humidity. Quantum chemical calculations further identified the H atom of the –NH group on the pyrazole ring as the key moisture-sorption site of DNP.

Abstract:To overcome the inherent energy-density penalty associated with conventional non-energetic fluoropolymer coatings while simultaneously enhancing the ignition performance and hydrophobicity of micron-sized aluminum powder， a novel energetic fluorine-containing compound， 1，4-dinitro-5，5-bis（trifluoromethyl）hexahydroimidazo［4，5-d］imidazole-2（1H）-one （DNG）， was chemically grafted onto the aluminum surface via a Mannich reaction using γ-aminopropyltriethoxysilane （KH550） as the coupling agent. A series of Al@KH550@DNG composite particles with varying DNG contents were fabricated， and their crystal structure， surface chemical composition， microstructure， thermal decomposition behavior， ignition and combustion characteristics， and hydrophobicity were systematically investigated by XRD， FT-IR， XPS， SEM， TG-DSC， laser-ignition high-speed videography， and contact-angle measurements. The results demonstrate that DNG forms a stable， uniform molecular layer on the aluminum surface through C-N covalent bonds. At an optimal DNG mass fraction of 10 wt%， the exothermic enthalpy of the composite increases substantially from 5891.14 J·g^-1 to 14835.28 J·g^-1 （a 152% enhancement）， the ignition delay time is shortened from 220 ms to 44.5 ms， the combustion duration is extended from 457.5 ms to 955.5 ms， and the water contact angle rises from 56.7° to 133.0°， indicating markedly improved hydrophobicity. By constructing a chemically grafted interfacial energetic fluorine-containing layer， this strategy simultaneously preserves high energy density and effectively enhances the energy release rate， ignition and combustion performance， and moisture resistance of aluminum powder， offering an innovative route for developing high-performance aluminum-based fuels for solid propellants.

Abstract:To address issues such as uneven component distribution and significant variability in ignition performance of B/KNO₃ propellants prepared by traditional mechanical mixing methods， microfluidic technology was employed to achieve in-situ preparation of this propellant. The numerical simulation was carried out by FLUENT software to optimize the droplet formation conditions， and the optimal flow velocity ratio of continuous phase and dispersed phase was determined to be 10∶1. Under this process， the in-situ recrystallization of KNO₃ and the in-situ doping of graphene oxide and Fe₂O₃ were realized with the help of microfluidic technology， using absolute ethanol as the continuous phase and KNO₃ aqueous solution containing boron powder （b）， phenolic resin （PF） and graphene oxide/Fe₂O₃ as the dispersed phase. Structural and thermal properties were characterized using SEM， EDS， BET， FTIR， and TG-DSC； thermal decomposition kinetics parameters were calculated via the Kissinger method， and combustion time consistency was verified through parallel combustion tests. Results demonstrated that microfluidically prepared B/KNO₃ propellants exhibited uniform component distribution， smaller particle sizes， a 104.5% increase in specific surface area compared to mechanically mixed samples， and a reduction in average combustion time from 80.67 ms to 64.33 ms （a 20.2% improvement）. The synergistic effect of the thermal conductivity of graphene oxide combined with the catalytic activity of Fe₂O₃ significantly lowered the activation energy of the system， primary decomposition onset temperature， and exothermic peak temperature， further accelerating combustion rates. Optimal addition concentrations were determined as 0.8% graphene oxide and 2% Fe₂O₃， reducing the average combustion duration to 50.33 ms.

Abstract:To address the problems of irregular morphology and poor mechanical properties of conventional hexanitrostilbene （HNS） crystals， HNS/F₂₆₀₄ microspheres were fabricated via microfluidic technology. By combining Brazilian splitting tests with finite element simulations， the mechanical properties and enhancement mechanism of the as-prepared microspheres were systematically investigated.The results show that HNS/F₂₆₀₄ microspheres with good sphericity and smooth surfaces can be obtained when the dispersed phase flow rate is 0.05 mL·min^-1， the continuous phase flow rate is 2.0 mL·min^-1 （flow rate ratio of 1∶40）， and the collection temperature is 60 ℃. The microspheres retain the original crystalline structure of HNS， while their peak thermal decomposition temperature is 4.6 ℃ lower than that of pure HNS.Brazilian splitting tests indicate that the pure HNS pellet has a peak load of 0.0065 kN and exhibits brittle fracture characteristics； in contrast， the peak load of the HNS/F₂₆₀₄ microsphere pellet increases to 0.072 kN， and its post-peak stress-displacement curve shows multi-stage attenuation， reflecting a transition to ductile fracture. The crack propagation morphology obtained from finite element simulations is in good agreement with the experimental fracture features. The HNS/F₂₆₀₄ composite microspheres prepared by microfluidic technology exhibit a remarkable toughening effect.

Abstract:To address the technical bottleneck of conventional metal fuels， which struggle to balance high energy content and efficient energy release， the microstructure and composition， combustion process， and energy performance of AlTiV alloy powders were investigated using scanning electron microscopy/energy dispersive spectroscopy （SEM/EDS）， X-ray diffraction （XRD）， flat-flame burner， oxygen bomb calorimeter， and thermogravimetry-differential thermal analysis （TG-DSC）. The explosion heat performance of hydroxyl-terminated polybutadiene （HTPB） propellants incorporated with the alloy powders was verified via an adiabatic method. The results show that AlTiV alloy powders exhibit a highly spherical morphology and a body-centered cubic （BCC） solid solution structure， and their combustion process proceeds through four successive stages： ignition， self-sustained combustion， micro-explosion， and dispersed combustion. Increasing titanium content shortens the ignition delay and micro-explosion duration while enhancing micro-explosion intensity. Vanadium oxides can disrupt the surface oxide layer， thus promoting the gas-phase combustion of aluminum vapor. Among the samples， the Al₃₀Ti₂₅V₄₅ alloy powder （designated as ATV30） delivers a combustion efficiency of 97.35% and a volumetric calorific value of 86590 J·cm^-3. It initiates rapid oxidation at 600 ℃ with an oxidation efficiency of 97.62%. When ATV30 replaces one quarter of the aluminum powder in HTPB propellant， the volume explosion heat of the propellant increases by 2.3%. It is confirmed that AlTiV alloy powders can improve the explosive heat performance of propellants through the synergistic effect of micro-explosion and gas-phase combustion， providing a theoretical foundation and experimental support for the application of novel metal fuels in solid propellants.

Abstract:To reveal the influence laws and action mechanisms of film thickness and working conditions with/without an acceleration chamber on the laser ignition performance of thin films， photoelectric detectors， high-speed cameras， spectrometers and schlieren system were adopted to investigate the laser ignition sensitivity， ignition delay time， plasma characteristics of laser-ablated thin films， laser-induced plasma shock waves and particle motion characteristics of thin films for B/KNO₃/PF energetic powder under various film thicknesses and acceleration chamber thicknesses.The results show that the 204 nm-thick Ti/Al-1 thin film facilitates the laser ignition process， lowering the laser ignition energy fluence threshold from 3.94 J·cm^-2 （without a thin film medium） to 3.67 J·cm^-2. By contrast， the 488 nm-thick Ti/Al-2 and 874 nm-thick Ti/Al-3 thin films raise the ignition energy fluence threshold， with corresponding threshold values of 4.23 J·cm^-2 and 4.85 J·cm^-2， respectively. The laser ignition delay time increases in the order of Ti/Al-1， without thin film medium， Ti/Al-2 and Ti/Al-3， following the same trend as the laser ignition energy fluence threshold. As the film thickness rises， both the electron temperature and electron density of laser-ablated film plasma decrease. When an acceleration chamber with a thickness of 0.1 mm and inner diameter of 0.6 mm is placed between the thin film and energetic powder， no obvious variation occurs in the laser ignition sensitivity of the powder. The minimum ignition delay times of the three film systems are shortened by 0.21 ms， 1.64 ms and 2.67 ms compared with the condition without an acceleration chamber， and the optimized delay times are 1.6 ms， 1.0 ms and 1.3 ms in sequence.There exists an optimal matching relationship between thin film medium thickness and acceleration chamber thickness. The Ti/Al-2 and Ti/Al-3 thin films achieve the optimal ignition performance when matched with 0.1 mm-thick and 0.2 mm-thick acceleration chambers， respectively.

Abstract:Aiming at the problems of low sensitivity and poor selectivity of spectrophotometry and titration in the analysis of hydroxylamine nitrate content in energetic material production wastewater， a high sensitivity analysis method based on gas chromatography tandem mass spectrometry （GC-MS） was developed for the determination of trace hydroxylamine nitrate in water. Through acetone derivatization， hydroxylamine nitrate reacted with acetone to produce acetone oxime which was easy to be tested by gas chromatography. The derivatization conditions and GC-MS parameters were optimized， and N，N-dimethylnitrosamine （NDMA） was used as the internal standard for quantitative analysis. The results showed that the linear relationship of hydroxylamine nitrate in the linear range （R²>0.999） was good， the detection limit was 0.015 mg·L^-1， the recovery rate was 95%-108%， and the relative standard deviation was 3.6%-5.7%. This method has been successfully applied to the analysis of industrial waste water. It has the advantages of simple operation， high sensitivity and strong anti-interference ability. It provides an efficient and accurate analytical method for the monitoring of hydroxylamine nitrate in environmental water.

Abstract:To address the issue of significant attenuation and strong scattering of ultrasonic waves in solid propellants， which prevents existing ultrasonic transducers from detecting all internal defects， a nondestructive testing research method using ultrasonic laminated transducers is proposed. Based on the research of domestic and international scholars， this study first proposes leveraging the high transmission energy characteristic of laminated transducers to mitigate attenuation and scattering problems during ultrasonic propagation in solid rocket propellants. A 1 MHz four-layer ultrasonic transducer is designed. This transducer converts a planar acoustic field into a cylindrical acoustic field through crystal stacking， thereby enriching echo information and improving defect resolution. Based on acoustic field simulations of the ultrasonic laminated transducer， a 1 MHz four-layer ultrasonic transducer is developed. Experimental comparisons with domestic and international transducers of similar specifications show a 20 dB improvement in gain. Finally， an ultrasonic automated inspection system for solid rocket propellants is established， enabling online inspection of solid rocket propellants. The results indicate that the developed inspection equipment can accurately detect the smallest artificial blind holes measuring Φ1.2 mm × 5 mm （depth） as well as natural inclusion defects， achieving qualitative and quantitative nondestructive testing of all internal defects in solid rocket propellants.

Abstract:Leveraging the non-contact nature and penetration capability of continuous-wave terahertz imaging， this study proposed a nondestructive detection method for metallic foreign objects in energetic materials.Terahertz imaging experiments were conducted on four types of metallic foreign objects covered by energetic-material layers with thicknesses of 0.5-2.0 cm， and a corresponding terahertz image dataset was established. Based on this dataset， a lightweight recognition model based on YOLO26-Partial was developed for metallic foreign object detection. In addition， an enhanced generative adversarial network， termed EDGAN， was proposed for terahertz image super-resolution reconstruction by integrating an attention mechanism with a deep residual structure. Experimental results demonstrate that the proposed recognition algorithm achieves an average recognition accuracy of 99% for the four types of metallic foreign objects while reducing model complexity. Compared with ESRGAN， the proposed reconstruction algorithm achieves average improvements of 5.70% and 1.36% in peak signal-to-noise ratio （PSNR） and structural similarity index （SSIM）， respectively. The proposed method enables both accurate recognition and high-quality super-resolution reconstruction of metallic foreign objects in energetic materials， providing a feasible technical approach for nondestructive inspection in related applications.