Abstract:To improve the compatibility of dihydroxylammonium 5，5′-bitetrazole-1，1′-diolate（TKX-50） with nitrocellulose（NC）， silane coupling agent （KH550） was used as the coating agent and three TKX-50/KH550 composites （TK1， TK2， TK3） were obtained.The morphology， structure and thermal stability of the composites were studied by using scanning electron microscopy （SEM）， Fourier infrared spectroscopy （FTIR）， and differential scanning calorimetry （DSC）. Accelerating rate calorimeter （ARC） and DSC were used to examine the compatibility of TKX-50/KH550 composites with NC. The results show that the apparent activation energy of thermal decomposition of the prepared TKX-50/KH550 composites are 190.03， 195.82 and 194.42 kJ·mol^-1 respectively higher than that of TKX-50 （138.86 kJ·mol^-1）， indicating the thermal stability of TKX-50 is improved by KH550 coating. In adiabatic conditions， the initial thermal decomposition temperature of the mixtures of TKX-50/KH550 composites and NC are 14.93， 18.18 and 17.90 ℃ respectively higher than that of TKX-50 and NC. After coated with KH550， the compatibility of TKX-50 and NC is improved， and the compatibility level of TKX-50/KH550 composites and NC is raised from Level 3 to Level 2.

Abstract:Boron-based hypergolic ionic liquids， which exhibited low viscosity， short ignition delay time and low cost， were considered as the powerful candidate for conventional liquid propellants. Here， the research progress of design， synthesis and physical chemical properties on boronium-anion-based HILs were systematically reviewed. The theoretical and applied studies including thermal decomposition， hypergolic reaction， combustion mechanism and relationship between structure and performance were briefly summarized. The practical application and development tendency of boronium-anion-based HILs were also discussed．

Abstract:The fluorescence properties and fluorescence stability of 2，4，8，10-tetrabroitro-benzopyrido-1，3a，6，6a-tetraazapentylene （BPTAP） were comprehensively investigated. The spectral properties of BPTAP in different solvents （acetonitrile， methanol， tetrahydrofuran， acetone， trichloromethane， ethyl acetate， N"-N"-dimethylformamide， dimethyl sulfone）， content of water （0-100%）， pH （2.0-12.0） were studied in detail. The effects of light， temperature and pH value on the fluorescence stability of BPTAP solution were investigated， and the mechanism of fluorescence decay of BPTAP solution was analyzed by ultra performance liquid chromatography-high resolution mass spectrometry （UPLC-HRMS）. The results show that although BPTAP has four nitro groups， it exhibits strong green fluorescence in some organic solvents. The fluorescence intensity of BPTAP in acetonitrile is the highest， and its maximum absorption/emission wavelength is 460 nm/508 nm. Low content of water （≤10%） can increase fluorescence intensity of BPTAP， while high content of water （>10%） decrease the fluorescence of BPTAP sharply. BPTAP has higher fluorescence in acidic， neutral and weak alkaline conditions. When the pH value is above 9.0， the fluorescence of BPTAP decreases rapidly with the increase of pH value. BPTAP shows good stability in room temperature and natural light. The closer the light wavelength is to the maximum absorption wavelength of BPTAP and the higher the temperature， the worse the fluorescence stability of BPTAP. The increase of pH value not only reduces the fluorescence intensity of BPTAP， but also accelerates the decline of BPTAP fluorescence. The mechanism of fluorescence decay of BPTAP under alkaline condition is based on nucleophilic substitution. The nitro group at para site of pyridine ring is replaced by the hydroxyl group in alkaline solution to form a new compound 1 （the elemental composition ［M-H］^- is C₁₁H₃N₈O₇）.

Abstract:

Abstract:Compared with traditional casting method， composite solid propellant manufactured by additive manufacturing （commonly known as “3D printing”） technology exhibits a series of technical advantages， such as arbitrary grain configuration without mold limitation and continuously controllable formulation as well as performance. In order to improve printing effect， printing formulation and technical parameters of composite solid propellant based on light-curing molding were studied， and the performance of printed propellant samples was evaluated. In addition， comprehensive additive manufacturing of composite solid propellant and resistive temperature sensor was achieved by integrating resistive temperature sensor into the printed propellant samples， and the resistance values of temperature sensor at different temperatures were examined. The results show that solid propellant slurry with 83% solid content displays a good pre-curing effect by adding no less than 3% ultraviolet （UV）-curable resin. The slurry with 77% or 80% solid content can be extruded through a 0.26 mm diameter needle， while solid content reaching 81% or above requires a 0.5 mm diameter needle. The printed propellant sample comprising 81% solid content possesses good dimensional stability and unconspicuous appearance defects， but computed tomography （CT） results reveal the existence of lamellar pores inside the sample. The tensile strength and elongation at break of printed propellant sample are equal to 0.94 MPa and 15.63% at 20 ℃， respectively. At 60 ℃， the tensile strength and elongation at break of sample are 0.70 MPa and 14.63%， respectively. The printed propellant owns comparable tensile strength and reduced elongation at break compared to conventional casting propellant. The bonding strength between temperature sensor and propellant is 0.21 MPa， showing favourable bonding effect. The resistance of temperature sensor varies linearly with temperature within testing temperature range （20-60 ℃）， demonstrating good temperature monitoring capability.

Abstract:Inkjet printing technology is an advanced micro-manufacturing technology based on ink droplets， which integrates jetting technology， discrete stacking numerical control manufacturing， and computer-aided design. It is one of the important loading approaches for micro-structured energetic devices such as MEMS pyrotechnics. In the ink-jet printing process， the precise control of droplets is the key to improving the printability and accuracy of the targeted materials. Based on the systematic investigation of the inkjet printing forming mechanism， the physical characteristics of ink and the influence of printing process parameters on the formation of ink droplets were discussed， and the reason and control methods for the "coffee ring" effect were also summarized. The controlling strategies of droplet formation and deposition in the ink-jet printing process were described. At the same time， the application of ink-jet printing technology in booster， nano-thermite， etc. was reviewed， and the development direction of inkjet printing technology in energetic materials was prospected. The drop-on-demand and control with picoliter of ink-jet printing technology provides a prerequisite for the precise charging of micro-nano-structured energetic agents and has good application prospects in MEMS pyrotechnics and special-shaped energetic devices.

Abstract:The effect of crosslinking catalyst Copper 2，4-glutarate-cyclooctadiene complex dosage on the properties of polytriazole-crosslinked solid elastomer was studied. Propargyl-terminated ethylene oxide-tetrahydrofuran copolymer （PTPET）was used as an adhesive and polyazide compound as an curing agent， a series of polytriazole-crosslinked solid elastomers S1-S4 were prepared by adding crosslinked catalysts of 0.01%， 0.02%， 0.05% and 0.10%. The chemical structure， thermal stability， mechanical properties and network structure of polytriazole-crosslinked solid elastomers were characterized by FTIR， TG， equilibrium swelling method and DMA. It was found that PTPET elastomer is more stable than PET elastomer， the dosage of the catalyst did not influence the thermal stability of the elastomer， and the decomposition temperature for all samples is at 405 ℃. The elastomer S2 with 0.02% crosslinking catalyst has the most perfect network structure and the best mechanical properties， and the glass transition temperature is -67.4 ℃.

Abstract:The rapid development of additive manufacturing technology provides an effective way for the flexibility and adaptability of traditional solid propellant casting molding， however， to meet the requirements of the casting， the thermosetting solid propellants with good fluidity could not deposite layer by layer. In order to realize the additive manufacturing， the hydroxyl-terminated polybutadiene （HTPB） was modified by adding a small amount of styling aids. The rheological properties of the modified-HTPB and slurry made by using the modified-HTPB were studied. The rheological curve test results show that apparent viscosity and viscous flow activation energy of the modified-HTPB increase significantly with the decrease of temperature. The rheological property of the modified-HTPB solid propellant slurry is consistent with Herschel-Bulkley equation， and the fluidity of modified-HTPB solid propellant slurry increases with the increment of temperature. Besides， the slurry possesses high storage modulus（G′＞10⁴ Pa） and small loss tangent（ω＜10 rad·s^-1，G″/G′＜0.5） at ambient temperature， showing a low fluidity. A small amount of styling aids has little effect on the thermal decomposition behavior of the propellant， which promotes the 3D printing of the modified-HTPB solid propellant .

Abstract:3，3′-Diamino-4，4′-azofurazan （DAAzF） is one of the main impurities that produced during the synthesis of 3，3′-diamino-4，4′-azoxyfurazan （DAAF）. However， the effect of DAAzF on the thermal performance of DAAF remains unclear in the past. To this end， a doping strategy based on the dissolution-precipitation method was developed to prepare DAAF@DAAzF explosives by uniformly doping 0.5%-10% DAAzF into DAAF， and the effect of DAAzF on the thermal performance of DAAF@DAAzF explosives was investigated by using simultaneous thermogravimetry and differential scanning calorimetry. The doping of DAAzF decreases the melting point of DAAF-based explosives， with the greatest decrease from 246.4 ℃ to 239.3 ℃ occurring at 10% DAAzF content. For the first time， it is found that the eutectic mixture can be formed when the mass ratio of DAAzF/DAAF is 5/95. Further， the presence of DAAzF decreases the activation energies and pre-exponential factors of DAAF-based explosives during the initial decomposition. Therefore， DAAzF as an impurity accelerates the thermal decomposition of DAAF@DAAzF explosives and reduces their thermal stability.

Abstract:To explore the curing reaction behavior of 3，3-bis（azidomethyl）oxetane-tetrahydrofuran copolyether （PBT） and toluene diisocyanate （TDI） binder system， the effects of curing temperature， curing ratio and plasticizer on the curing reaction of PBT-TDI system were investigated by microcalorimetry， and the curing reaction kinetics and thermodynamics of PBT-TDI system were studied and analyzed. The experimental results show that： （1） the higher the curing temperature and the higher the TDI content， the faster the curing reaction； （2） increasing the amount of plasticizer bis（2，2-dinitropropyl）acetal/bis（2，2-dinitropropyl）formal （A3） and dioctyl sebacate （DOS） would reduce the curing reaction speed of the PBT-TDI system； （3） the curing reaction of the PBT-TDI system fits well with the n-th order reaction kinetic model with an activation energy of 12.81 kJ·mol^-1 and a pre-exponential factor of 1.48×10^-2 s^-1.

Abstract:To prevent the agglomeration of cobalt ferrite （CoFe₂O₄） nanoparticles and improve their catalytic decomposition performance for Octogen （HMX） and HATO （TKX-50）， graphitic carbon nitride （g-C₃N₄） was applied as CoFe₂O₄ nanoparticles dispersant carrier. The in suit preparation of CoFe₂O₄/g-C₃N₄ binary nanocomposites were achieved through solvothermal method. Corresponding composition， structure morphology and catalytic decomposition performance of CoFe₂O₄/g-C₃N₄ were investigated through X-ray powder diffractometer， scanning electron microscopy， fourier transform infrared spectrometer and differential scanning calorimeter. The results showed that the morphology of CoFe₂O₄/g-C₃N₄ composites is uniform and dense， which reduces the thermal decomposition peak temperature of HMX and TKX-50 by 7.0 ℃ and 41.3 ℃， respectively， and the apparent activation energy by 341.1 kJ·mol^-1 and 21.0 kJ·mol^-1， respectively. Moreover， the introduction of g-C₃N₄ increases the heat release amount. The results of residue analysis showed that the catalytic decomposition of HMX was very complete， while TKX-50 presents incomplete catalytic decomposition， and its residua formed micron bulk mixtures with CoFe₂O₄/g-C₃N₄.

Abstract:The development of new combustion catalysts plays a key role in high performance propellants. Herein， the metal-organic complexes Mg（Salen） and Pb（Salen） were synthesized and characterized using X-ray diffraction， fourier transform infrared， and scanning electron microscope. Their catalytic effects on the thermal decomposition of 1，3，5，7-tetranitro-1，3，5，7-tetrazolidine （HMX） were further investigated by differential scanning calorimetry. The results indicate that the thermal decomposition of HMX is evidently enhanced by the introduction of Mg（Salen） and Pb（Salen）. Compared with HMX， the decomposition peak temperatures of HMX/Mg（Salen） and HMX/Pb（Salen） dropped by 3.0 ℃ and 34.0 ℃， and theoretical apparent activation energies decreased by 7.7 kJ·mol^-1 and 34.4 kJ·mol^-1， respectively. The catalytic decomposition mechanisms of Mg（Salen） and Pb（Salen） are also elucidated by exploring the decomposition kinetics and the reaction function models.

Abstract:Meriting in green and pollution-free combustion products， large specific surface area， insensitive-safety ， large contact area with reactants and easy modification， nanocarbon has been widely focused on tuning the performances of energetic materials （EMs） such as high explosives， propellants and thermites. This work reviews the effects of nanocarbon on the decomposition characteristics， sensitivity， mechanical performances and combustion properties of EMs. In addition， it discloses the progresses in the detection， adsorption and degradation of EMs conducted by nanocarbon. The interaction mechanisms of typical nanocarbon materials （nano-diamond， fullerene， nanocarbon fiber， carbon nanotube and graphene） in EMs have been analyzed. Within this review， issues， challenges and promising research directions existing in the application of nanocarbon in EMs are highlighted and presented. （1） Optimizing the high-cost preparation processes of nano carbon. Easy agglomeration and large batch differences of nanocarbon. （2） Expanding the application scope of nanocarbon. Exploring the effects of new-type nanocarbon such as onion carbon and modified nanocarbon on the properties of energetic materials. （3） According to the specific environment and nanocarbon regulation mechanism， the application conditions of nanocarbon in improving the properties of energetic materials are optimized. It is expected that nanocarbon materials will provide a forum for future advancement in the modifications of multifunctional EMs.

Abstract:In order to establish a precise combustion heat measurement system and method suitable for energetic materials， a method and device for measuring the heat of combustion of energetic materials with tiny doses has been developed. This device is based on the thermal principle of differential heat flux and uses a three-dimensional thermopile consisting of 960 pairs of thermocouples as the core measuring element. The device was calibrated by using standard material benzoic acid. The heat of combustion of six typical energetic materials， including cyclotetramethylene tetranitramine， hexanitrohexaazaisowurtzitane， cyclotrimethylene trinitramine， 3，4-bis（3-nitrofurazan-4-yl）furoxan， 1，1-diamino-2，2-dinitroethylene and nitroguanidine， was measured by this device. The results show that the calorimetric coefficient of the instrument is （64.804±0.071） μV·mW^-1 and the corresponding relative uncertainty is 0.109%. The solid-phase standard molar heats of combustion （Δ_cU） of these six energetic materials at 298.15 K are -（2749.1±4.5）， -（3593.6±6.0）， -（2115.2±3.4）， -（3040.8±4.8）， -（1211.4±2.3） and -（898.4±2.0） kJ·mol^-1， respectively. The measurement results are in good agreement with the values reported in the literature， indicating that the developed small-mass combustion measurement device can be widely used in the determination of the energy of combustion of substances containing C， H， O， and N， especially precious samples and explosive substances.

Abstract:To solve the problems of igniting difficulty and combustion agglomeration， modification of Al powder by alloying and oxidant coating was studied. AP@Al/Ni composite fuels were prepared by acoustic resonance mixing technique. The heats of reaction of the composite fuels with different ammonium perchlorate （AP） contents were measured using a bomb calorimeter. The morphology characteristics of the optimized AP@Al/Ni composite fuel were analyzed by SEM. The thermal reactivity of AP， Al/AP mixture， Ni/AP mixture， and AP@Al/Ni composite fuel were comparatively studied by DSC/TG. The effects of additives including Al， Ni， and Al/Ni composite on the thermal decomposition kinetic parameters of AP were evaluated by the non-isothermal kinetic method. The results show that the heat of reaction of the composite fuel reaches its maximum when the mass content of AP is 38.90%， which is considered as the optimal content of AP in the formula. Compared with Al and Ni， the Al/Ni composite has the most significant influence on the thermal decomposition of AP， which reduces the peak temperature of AP in high temperature decomposition by 76.9 ℃ and increases the heat release by 84.8%. The apparent activation energy of AP decomposition in AP@Al/Ni composite fuel that obtained by Friedman method is 103.9 kJ·mol^-1， and this process obeys the three-dimensional random nucleation and nucleus growth （A3） model.

Abstract:To explore the detailed thermal decomposition properties of the mixture system consists of ammonium perchlorate-based molecular perovskite energetic material （H₂dabco）（NH₄）（ClO₄）₃ （DAP-4， where H₂dabco²⁺ refers to 1，4-diazabicyclo［2.2.2］octane-1，4-dianiumion） and dihydroxylammonium 5，5"-bistetrazole-1，1"-diolate （TKX-50）， the thermal decomposition characteristics and gas products of DAP-4 and DAP-4/TKX-50 mixtures were comparatively analyzed by using differential scanning calorimetry-thermogravimetry/mass spectrometry/fourier infrared spectroscopy； meanwhile， the changes of characteristic groups in the condensed phase of DAP-4 and DAP-4/TKX-50 mixtures with temperature were investigated by in-situ FTIR. Based on the explorations the thermal decomposition mechanism of DAP-4/TKX-50 mixture was proposed. The results showed that after mixing DAP-4 with TKX-50， DAP-4 had little effect on the thermal decomposition of TKX-50， while the heat generated by the thermal decomposition of TKX-50 made the reversible phase transition endothermic peak of DAP-4 disappeared， but hardly affected DAP-4′s thermal decomposition at high temperature. The thermal mass loss of DAP-4/TKX-50 mixture was divided into two stages. The mass loss of the first stage was 43.4% and the mass loss of the second stage was 52.4%， leaving 4.2% of the decomposition residue. The main gas products produced by thermal decomposition of DAP-4 and DAP-4/TKX-50 mixture were NH₃/H₂O/HNCO/HCN/CO/HCl/CO₂ and H₂O/NO/N₂O/HCl/NH₃/N₂/HNCO/HCN/CO/CO₂， respectively. The thermal decomposition mechanism of the DAP-4/TKX-50 mixture was proposed as follows： the reversible transfer of hydrogen ions occurs first in the molecule of TKX-50 to generate hydroxylamine and 1，1"-dihydroxy-5，5"-bitetrazole （BTO）， then hydroxylamine decomposed into small molecular gases at high temperature while the fragments generated by BTO decomposition partially polymerized into coupling products. Finally， the ionic bond of DAP-4 was broken， leading to instantaneous collapse of the cage-like skeleton. The strongly reducing and strongly oxidizing gas components underwent violent redox reactions at high temperatures and release a large amount of heat.

Abstract:To investigate the effect of deuteration on the vibrational properties of chemical bonds of triacetone triperoxide （TATP） and its thermal decomposition behavior， TATP and deuterated triacetone triperoxide （TATP-d₁₈） were prepared by using acetone and acetone-d₆ as raw materials， respectively， with hydrogen peroxide acting as the oxidant source and sulfuric acid as the catalyst. TATP and TATP-d₁₈ were characterized by nuclear magnetic resonance spectroscopy （NMR）， Fourier transform infrared spectroscopy （FTIR） and differential scanning calorimetry （DSC）. The non-isothermal reaction kinetic parameters of TATP and TATP-d₁₈ were calculated with Kissinger， Ozawa， and Friedman methods. The results show that the deuteration of TATP results in an evident red-shift phenomenon， and the ratio of the stretching frequencies of C—H（D） bonds （ν_C—H/ν_C—D） is about 1.36. The apparent activation energy of TATP-d₁₈ （E_K=80.54 kJ·mol^-1， E_O=83.56 kJ·mol^-1， E_F=72.27 kJ mol^-1） is higher than that of TATP （E_K=67.91 kJ·mol^-1， E_O=71.01 kJ·mol^-1， E_F=63.79 kJ·mol^-1）， indicating that TATP-d₁₈ has higher thermal stability. The calculated thermal explosion critical temperatures for TATP （T_b=402.37 K） and TATP-d₁₈ （T_b=423.46 K） also confirm that deuteration improves the thermal stability of TATP-d₁₈. Finally， the calculated thermodynamic parameters for the non-isothermal decomposition processes of TATP and TATP-d₁₈ indicate that TATP and TATP-d₁₈ would not spontaneously undergo thermal explosions.

Abstract:To promote the stable production and wide application of silver acetylide-silver nitrate （Ag₂C₂·AgNO₃）， the structural morphology and thermal decomposition characteristics were systematically studied by X-ray powder diffractometry， Fourier tranform infrared spectrometer， scanning electron microscopy， differential scanning calorimeter and thermogravimetric-mass-infrar- ed spectrometry techniques. The results indicate that the prepared Ag₂C₂·AgNO₃ sample is in the form of nanospheres with particle sizes ranging from 400 to 500 nm. There is only one exothermal decomposition process of Ag₂C₂·AgNO₃ with a peak temperature of 234.9 ℃， a weight loss of 8.72%， and a heat release of 1449 J·g^-1，at a heating rate of 10 ℃·min^-1. The apparent activation energy and pre-exponential constant of decomposition process are obtained as 108.9 kJ·mol^-1 and10^8.94 s^-1， respectively. Moreover， the gaseous decomposition products of Ag₂C₂·AgNO₃ were NO， NO₂ and CO₂.

Abstract:To alleviate the aggregates of n-Al particles and improve its combustion performance， high-energy low-sensitivity nitrochitosan （NCh） with a honeycomb network structure was used as coating agent to prepare a binary nanocomposite with uniform structure through an acoustic resonance method. The morphology， structure and combustion performance of NCh/n-Al were investigated by XRD， SEM， TEM and laser ignition， and compared with that of NC/n-Al composite. The results show that the prepared NCh/n-Al has uniform morphology and good dispersion. Compared with pure n-Al and NC/n-Al， the ignition delay time of NCh/n-Al is shortened by 6 ms and 20 ms， respectively. The combustion of NCh/n-Al is more complete， the condensed combustion products are mainly Al₂O₃， a very small amount of unburned Al and carbon residue， and the particle size is significantly smaller.

Abstract:In order to meet the requirements of explosives， thermoplastic elastomers with different number-average molecular weight （M_n） were prepared. Controllable polymerization and application of glycidyl azide polymer （GAP）-based energetic thermoplastic elastomers （GETPE） were conducted. The influence of polymerization medium and solid content on controllable polymerization of GETPE was investigated， and on-line viscosity monitoring on M_n was explored. The results show that M_n of GETPE can be accurately controlled by on-line viscosity monitoring. The error of M_n in the range of 20000-50000 can be tuned within ±2000， and the error rate can be controlled within 5%. GETPE has excellent compatibility with commonly used explosives and good application potential in high solid content propellant and high energy polymer bonded explosives （PBXs）.

Abstract:Mechanically mixed and electrostatic sprayed RDX/NC/AP/Al composite explosive using nitrocellulost （NC） as binder， ammonium perchlorate （AP） as oxidant， cyclotrimethyltrnitramine （RDX） and nano aluminum powder （Al） as combustion agent were prepared based on zero oxygen balance. The morphology， structure， thermal properties， combustion process and mechanical sensitivity of the different samples were analyzed by the scanning electron microscopy （SEM）， the Fourier transform infrared spectroscopy（FT-IR）， thermogravimetric differential scanning calorimeter （TG-DSC）， mechanical sensitivity and high-speed photography. The component（NC， RDX， AP and Al） in RDX/NC/AP/Al composite explosives obtained by both method are physical composite. However， the microstructure of mechanically mixed RDX/NC/AP/Al demonstrated in spheres and the electrostatic sprayed samples are microspheres. The mass loss process of RDX/NC/AP/Al composite explosive obtained by two methods contained two stages （200-210 ℃ and 250-350 ℃）. The first stage is the decomposition of part of RDX and AP， while the second stage is the decomposition of the remaining RDX and NC. Compared with the mechanical mixed samples， the activation energy and the critical temperature of thermal explosion of electrostatic sprayed RDX/NC/AP/Al increased by 41.25 kJ·mol^-1 and 4.09 K， respectively. Besides， the mechanical sensitivity is reduced， and the combustion rate is also improved.

Abstract:In order to explore a continuous， safe and controllable microfluidic synthesis strategy of emulsion explosive， silicon-based microporous array chips with four apertures（10 μm，20 μm，30 μm，40 μm） were designed and prepared by MEMS technology， and the microfluidic reaction device of emulsion explosive was constructed. It is found that the main factors affecting the droplet size of dispersed phase in latex matrix are micropore diameter and continuous phase velocity. The effects of pore size and oil-water two-phase flow rate on the particle size distribution and exothermic properties of emulsion droplets were studied. The results show that the particle size distribution of dispersed droplets in the matrix is the narrowest when the pore size is 30 μm and the continuous phase flow rate is 0.5 mL·min^-1 and D₅₀=8.169 μm. Microporous array chip can generate highly homogeneous droplets in batch， which provides a new choice for emulsification in the preparation of emulsion explosive.

Abstract:The comprehensive performance of explosives depends not only on their chemical components， but also on their structures and morphologies to a greater extent. Microfluidics has become a new research focus owing to its superb mass transfer and heat transfer efficiency， precise parameter control and intrinsic safety. This paper analyzed and summarized the research status of droplet flow and continuous flow in the aspects of particle size， particle size distribution， crystal morphology and aggregate structure of primary and high explosives. The stable reaction environment and flexible residence time of the droplet flow are applicable to the structural control of the primary explosives， and the superior size uniformity and monodispersity of the droplet flow are appropriate for the preparation of spherical explosive particles. The high mixing efficiency of the continuous flow is in line with the crystalline properties of the high explosive. Combined with the deficiencies of current related research in post-processing methods， theoretical applicability， microfluidic manipulation methods and the degree of intelligence， suggestions and ideas for the further development of microfluidic technology in the field of explosives were put forward.

Abstract:Hexanitrohexaazaisowurtzitane （CL-20） and nano-aluminum powder are commonly used for the improvement of energy density in explosive formulations， however， the high mechanical sensitivity of CL-20 or their mixture has been impeded further applications. Therefore， it is very meaningful to obtain a low-sensitivity of CL-20 and Al uniform mixture. In this paper， the Pickering emulsion was prepared by using nano-aluminum powder modified by perfluorocarboxylic acid as the surfactant （F-Al）， and the ethyl acetate solution of CL-20 and TNT as the oil phase. The influence law of F-Al powder content and static duration on the stability of the emulsion was investigated. The spheroidicity core-shell CL-20/TNT co-crystal@Al composite was successfully prepared. Its morphology， crystal form， thermal decomposition properties， safety， etc. were characterized. Results show that stable emulsions can be obtained when the content of F-Al powder is 1%， 10%， and 20% and static duration is less than 100 min. XRD results showed that the CL-20 and TNT cocrystals was obtained. The crystal size （20-40 μm）， the ellipsoid-like morphology， the uniformly coated nanosized F-Al powder were shown by the SEM images. An H₅₀ value of 35 cm and a friction sensitivity explosion probability of 30% have been realized for that of composites， which is much higher than that of CL-20. The preparation method used in the present paper does not sacrifice the energy density in the spheroidicity core-shell CL-20/TNT co-crystal/Al composite， which is expected to provide a pathway to the design and prepare of high-energy propellants and explosives containing CL-20 and Al.

Abstract:A measurement method of explosive crystallization thermodynamic parameters based on optofluidics was proposed to obtain the crystallization thermodynamic parameters such as solubility and metastable zone width of explosive crystal， and the applicability of this method was verified by taking HNS explosive as a sample. The solubility of HNS in DMSO/DMF solvent system with volume ratio of 10∶0， 7∶3， 5∶5， 3∶7 and 0∶10 from 318.15 to 353.15 K and the metastable zone width of HNS in the above DMSO/DMF solvent system from 318.15 to 333.15 K were measured with a step of 5 K. Apelblat model and λh model were employed to fit the collected solubility data. The effect of solvent system on the metastable zone width was studied， and the crystallization parameters were screened. According to the classical nucleation theory， the apparent nucleation order m of HNS was calculated， and the nucleation mechanism of HNS by cooling crystallization was analyzed. The results indicate that the measurement method of crystallization thermodynamic parameters based on optofluidics exhibit exceptional applicability to HNS crystals. With the increase of temperature and the volume ratio of DMSO in the system， the solubility of HNS increases. With the increase of DMSO volume ratio in the system， the width of metastable zone becomes narrower. The optimum crystallization conditions are as follows： pure DMSO is utilized as solvent， the solution temperature is set at 333.15 K， and the solute concentration is 0.029 g·mL^-1. The value of m is approximately 4， which is not affected by the initial temperature. It can be inferred that the nucleation mechanism of HNS belongs to continuous nucleation.

Abstract:Nano 2，6-diamino-3，5-dinitropyrazine-1-oxide （LLM-105） was prepared by ultrasound-assisted microfluidic technology based on the solvent and non-solvent method to improve the morphology and reduce the particle size. The microscopic morphology and crystal structures of the samples were characterized by field emission scanning electron microscopy （FE-SEM） and X-ray diffraction （XRD）. In addition， The promotion of fluid mixing by ultrasonic method was demonstrated by fluid visualization. The results showed that the spherical particles prepared by ultrasound were smaller and homogeneous， with an average particle size of 137.65 nm. Meanwhile， the crystal structures remained unchanged from the raw material. Differential scanning calorimetry （DSC） showed that the thermal decomposition temperature of nano-LLM-105 was reduced compared to the raw material， demonstrating that ultrasonic assistance can not only improve the efficiency of preparing nano-LLM-105， but also significantly reduce the particle size.

Abstract:The conventional lead azide （Pb（N₃）₂， LA） preparation process has problems such as the risk of self-explosion. Aiming at the above problems， the spin-T microfluidic chip with the characteristics of short diffusion distance， large specific surface area， and continuous reaction was used as a microreactor. And then， the LA primary explosive synthesized by microfluidics was spherically modified by using the flow-focusing droplet chip. The effects of the flow rate， crystal form control agent， and other factors on the product were investigated by SEM， XRD， and DSC. The sensitivity and explosion performance of microfluidic LA， microsphere LA， and powder LA were compared. The results show that by controlling the microfluidic reaction parameters， the particle size of the LA can be effectively controlled， and they were all α-type. After the spheroidization， the impact sensitivity H₅₀ （25.5 cm to 12.1 cm） was significantly improved， but the electrostatic spark E₅₀ （1.98 kV to 2.97 kV） and flame sensitivity L₅₀ （26.3 cm to 16.1 cm） were reduced. At the same time， the detonation pressure was increased （by 63.6%）. It shows that the microfluidic technology was an effective method that can safely prepare and modify the LA primary explosive， which provided an idea for the controllable preparation and regulation of sensitive primers.

Abstract:To control the morphology， particle size distribution and coating covering effect of high polymer binder explosives （PBXs）， TATB/F2602 microspheres could be prepared via high sensitivity droplet microfluidic technology， and investigated the effects of binder content and flow rate on the morphology and particle size of TATB-based microspheres. Moreover， it studied the morphology， structure， composition and thermal behavior of microsphere samples systematically using scanning electron microscopy， X-ray diffraction， specific surface area， DSC and TG， respectively. Results show that， when the binder content is 5%， the microspheres have smooth surfaces， regular spherical shapes and high spherical monodispersity， and the average roundness is 0.921 （span=0.04）. With the increase of flow ratio， the D₅₀ of microsphere sample decreased from 51.73 to 44.31 μm， and the particle size distribution is narrow （span<0.4）. Fluororubber （F2602） is uniformly distributed in the interior and surface of TATB microspheres， and uniform coating of TATB particles delay the thermal decomposition of microspheres by 4.08 ℃. Compared with raw TATB， the true density of TATB/F2602 increases to 1.9780 g∙cm^-3 during spheroidization. The droplet microfluidic technology can effectively control the morphology and particle size of explosive microspheres， and provide experimental reference for the spherical preparation of polymer bonded explosives.

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:In the present work it is found that the pyrotechnic composition VS-2 can be initiated with flash lamps IFC-500 and EVIS. VS-2 pyrotechnic composition contains 90% of mercury（Ⅱ） 5-hydrazinotetrazolate perchlorate and 10% of optically transparent copolymer of 2-methyl-5-vinyltetrazole and methacrylic acid （PVMT）. We have found that the flash lamps make it possible to initiate combustion of VS-2 composition with its transition to detonation both in cylindrical charges placed in brass caps of 5 mm diameter and 2 mm high， and film charges with 10 mm×80 mm in size and surface weights of 60 mg·cm^-2 and 90 mg·cm^-2， showing ignition delay times 10 μs and 3 μs， respectively. We also measured detonation velocities for VS-2 composition film charges， which were 4375-4505 m·s^-1 （of the charge being surface mass 60 mg·cm^-2） and 4221-4281 m·s^-1 （of the charge being surface mass 90 mg·cm^-2） and their blasting action on the aluminum plate. The depths of the normal shock wave imprints at the charge-barrier interface were 0.6-0.7 mm （for surface mass of the film charges 60 mg·cm^-2） and 1.2-1.3 mm （for surface mass of the film charges 90 mg·cm^-2）.

Abstract:The pyrotechnic formulation， that emitting purple light by using the synergetic effect of multi flame colorants， was designed and optimized theoretically. Based on the principle of additive color mixing， one purple-light-emitting pyrotechnic formulation containing flame colorants that generating red and blue colors was proposed. The types and contents of different colored light emitters were determined by REAL program. The color coordinates， wavelengths， color purities and chromaticity diagrams of different formulations were calculated by MATLAB program， and then the optimized pyrotechnic composition with purple light was determined. The theoretical results showed that the optimal formulation of purple-light-emitting pyrotechnics was Sr（NO₃）₂/2CuCO₃·Cu（OH）₂/Al/C₆H_9.6O_1.6 with the ratio of 48/32/12/8. The oxygen balance of the formulation was -0.11 g·g^-1 and the colored light emitters were Sr， SrO， SrOH， CuO， CuOH， and CuH， respectively. The purple chromaticity coordinate point was （0.2449，0.1497）. The virtual dominant wavelength of purple light was 446 nm， and the color purity was 0.40. The experimental measurements of the above formulation showed that the chromaticity coordinate point was （0.2425，0.1588）， the virtual dominant wavelength of purple light was 439 nm， and the color purity was 0.44. The purple light was actually produced by the mixing of red light （766 nm） and blue light （418 nm）， with good purple effect. The simulation results are in good agreement with the experimental results. This design method can provide a theoretical basis for the formulation optimization of other colored-light-emitting pyrotechnic compositions with multi flame colorants and the study of related problems.

Abstract:In order to design the B/KNO₃ （BPN） ignition powder formula with good combustion performance and compatibility with the direct ink writing technology， seven BPN-based ignition powder ink were designed and prepared by direct ink writing technology with different binders including polyvinylidene fluoride （PVDF）， poly （vinylidene fluoride-trifluorochloroethylene） F₂₃₁₁， poly （vinylidene fluoride-hexafluoropropylene） F₂₆₀₂， poly （vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene） F₂₄₆₁， ethylcellulose （EC）， nitrocellulose （NC） and PVDF/NC. The effects of different binder on the formability， ignition/combustion and thermal decomposition performance were investigated. The results show that the change of binder composition could result in the differentiation of the consistency index of BPN ink. The order of consistency index of different ink is EC/B/KNO₃>PVDF/B/KNO₃>PVDF/NC/B/KNO₃>NC/B/KNO₃>F₂₃₁₁/B/KNO₃>F₂₆₀₂/B/KNO₃>F₂₄₆₁/B/KNO₃. The formability of the ink depend on its consistency index. The rectangularity variation tendency of the samples prepared by direct ink writing technology is consistent with the consistency index. The BPN-based ignition powder containing fluorine rubber presented a higher burning rate and a shorter ignition delay. Meanwhile， the burning rate is faster when the H content is higher in the fluorine rubber. The order of linear burning rate of the BPN-based ignition powder containing different rubber is： PVDF/B/KNO₃>F₂₆₀₂/B/KNO₃>PVDF/NC/B/KNO₃>NC/B/KNO₃>F₂₄₆₁/B/KNO₃>F₂₃₁₁/B/KNO₃>EC/B/KNO₃. However， cellulose binder did not present any significant contribution to reduce the ignition delay. Adding fluorine rubber can reduce the initial reaction temperature of BPN-based ignition powder by about 145 ℃. NC can reduce the initial reaction temperature of the main reaction of the powder by 45 ℃. The addition of EC can only reduce the initial reaction temperature of the main reaction by about 5 ℃.

Abstract:The mixing uniformity and processing safety of widely used zirconium/lead tetroxide （Zr/Pb₃O₄） composites are indispensable. In the current paper， a Zr/Pb₃O₄ microcapsule bonded with the adhesive alginate was prepared by crosslinking the liquid phase with sodium alginate（SA） and Ca²⁺ in aqueous phase to form calcium alginate （CA） gel. The morphology， particle size， sphericity， fluidity and apparent density of CA/Zr/Pb₃O₄ microcapsules and the traditional-made NC/Zr/Pb₃O₄ controlled sample were evaluated. The average particle size， variance， sphericity and repose angle of CA/Zr/Pb₃O₄ microcapsules is measured to 517.10 μm， 44.21 μm， 0.90， and 27.44°， respectively. The flame sensitivity， burning rate， flame length and sensitivity of CA/Zr/Pb₃O₄ microcapsules were tested to 65.38 mm， which was lower than that of Zr/Pb₃O₄ powder （81.83 mm）. Besides， the combustion rate deviation of CA/Zr/Pb₃O₄ microcapsules and Zr/Pb₃O₄ powder is 6.86 and 12.04， respectively， implying an excellent combustion consistency. Furthermore， much more flame length of 17.1 mm and burning particles than Zr/Pb₃O₄ were obtained in of CA/Zr/Pb₃O₄ microcapsules. In addition， a reduced the electrostatic sensitivity of CA/Zr/Pb₃O₄ microcapsules （156.25 mJ） and Zr/Pb₃O₄ powder （0.71 mJ） were realized. More importantly， the water-phase preparation carried out in the current paper may pave a high-safety and universal way for a variety of pyrotechnic agents.

Abstract:Three energetic coordination compounds with strong reducibility were prepared with cyanoborohydride （CBH） as anion， 1-vinyl imidazole （VIM） as ligand and transition metals Co， Mn and Ni as central ions. The crystal structures were determined by single crystal X-ray diffraction and their molecular formulas are Co（VIM）₄（CBH）₂， Mn（VIM）₄（CBH）₂ and Ni（VIM）₄（CBH）₂， respectively. The thermal decomposition performance， oxygen bomb calorimetry and mechanical sensitivities of the complexes were tested. The results show that the complexes have high burning calorific capacity （26.5-29.1 kJ·g^-1）， low friction sensitivity （>360 N） and impact sensitivity （>40 J）. Hypergolic testing with white fuming nitric acid shows that the complexes can combust spontaneously， and the ignition delay time is short （4-13 ms）， which confirm the high reduction activity of the complexes. To explore the application of active coordination compounds in initiating explosive devices， three new composite igniting powders were obtained by mixing three complexes with sodium bromate in the mass ratio of 1∶7， respectively. The composite powders were ignited and tested with electric heating wire. After being ignited by electric heating wire， the three composite agents can burn continuously and produce large flame. Results show that the composite agents have potential applications as new ignition agents.

Abstract:

Abstract:2，4-MDNI/DNTF eutectic system was prepared by using 1-methyl-2，4-dinitroimidazole （2，4-MDNI）， a high energy insensitive explosive， to improve the high sensitivity and high melting point of the dynamite carrier 3，4-dinitrofuroxan （DNTF）. The melting and liquefaction processes of 2，4-MDNI/DNTF with different ratios were studied by differential scanning calorimetry （DSC）， and the T-x phase diagram was established. The melting and decomposition processes of 2，4-MDNI， DNTF and 2，4-MDNI/DNTF eutectic at different heating rates were studied. The kinetic parameters of 2，4-MDNi， DNTF and their eutectic were calculated by flynn-wall-Ozawa method， Doyle method and Kissinger method respectively. XRD and SEM analysis were carried out for the three substances. The hyposensitivity of 2，4-MDNI to DNTF was studied by sensitivity test.The detonation properties of 2，4-MDNI/DNTF eutectic were calculated by using EXPLO5. The results show that the molar composition of 2，4-MDNI/DNTF eutectic is 51∶49， and the average melting point is 92.7 ℃. As the heating rate increases， both melting and decomposition reactions are delayed. The activation energy E_a and pre-exponential factor A of thermal decomposition of eutectic are 146.0 kJ·mol^-1 and 4.09×10¹³， respectively. In XRD test， the low eutectic of 2，4-MDNI/PETN generates a new diffraction peak at 2θ=18.60°. The microstructure of the solidified surface is obviously better than that of DNTF. The impact and friction sensitivities of 2，4-MDNI are both 0%.The impact sensitivity and friction sensitivity of eutectic are 64% and 52%， respectively. The theoretical density of 2，4-MDNI/DNTF eutectic is 1.844 g·cm^-3， and the calculated detonation velocity is 8705 m·s^-1. The eutectic of 2，4-MDNI and DNTF was prepared with ideal melting point and good thermal stability. At the same time， the sensitivity of DNTF can be significantly reduced while maintaining its high energy level.

Abstract:In order to improve the low-temperature resistance of emulsion explosives （EE）， dimethyl sulfoxide （DMSO） was added into the aqueous phase of emulsion explosive matrix （EEM）. The crystallization rate， and microscopic structure and detonation performance of brisance of the prepared EEM were studied. And the thermal decomposition characteristics of EEM were also tested thermogravimetry-derivative thermogravimetry （TG-DTG） technology. The results show that adding 1.5% （mass fraction） of DMSO can delay the time for the EEM to reach the maximum crystallization rate from 24 days to 51 days under the condition of freezing at -20 ℃， compared to the EEM without DMSO. After being frozen for 12 days， the EEM containing DMSO has a more uniform distribution of emulsion particles. DMSO （1.5%） can increase the brisance of EE by 29.9%. The addition of DMSO has no obvious effect on the thermal decomposition process of EEM， but the apparent activation energy of EEM decreased with the increase of the DMSO content. When the DMSO content reached 1.5%， the apparent activation energy of EEM decreased by about 18.5%

Abstract:Energy Coordination Compound （ECC） has become one of the research hotspots in recent years because of its diverse Coordination modes between different metal elements and ligands， and it is expected to obtain energetic materials with highly adjustable properties. In this paper， the ways and types of assembling ECC with different ligands are reviewed， and the applications of ECC and its functional materials as initiators， propellant catalysts， flammable agents and oxidants of thermite， pyrotechnics colorants are reviewed. Studies have shown that the energetic complexes formed after the coordination of different metal ions and nitrogen-rich ligands show great potential in the field of new energetic materials， and can meet the requirements of energy， sensitivity and other properties through the change of the type and number of ligands. The law of ECC synthesis is summarized and how to improve the energy characteristics and expand the application in the future is prospected.

Abstract:This study probed the influence of compounds containing NH_n （n=0-4） groups such as ammonium perchlorate （AP）， guanidine nitrate （GN）， nitroguanidine （NQ）， N-methyl-4-nitroaniline （MNA） and cyclotetramethylene-tetranitramine （HMX） on the solidification process and solidification temperature of 2，4-dinitroanisole （DNAN）. The effects of the type of additives and AP content on the solidification temperature of DNAN were disclosed by a DSC and an optical microscope technique. Furthermore， as-calculated solidification linear velocity and the characteristics of dynamic crystallization process were analyzed based on the solidification process of addictive-containing DNAN in thin layer observed by microscope. The influence of the additives on the formability of the DNAN was studied by cross-section images of a Φ20 mm test pieces. In addition， relationships between solidification enthalpy and corresponding temperature of DNAN was studied based on crystallization thermodynamics. Besides， the mechanisms towards the influences of NH_n compounds on DNAN solidification was analyzed and verified. The results showed that an remarkable-increased solidification temperature of DNAN was achieved by the AP， while being slightly influenced by the AP content and other compounds like GN， NQ， MNA and HMX. The lowest solidification line rate of AP containing object with dendrite-like crystallization could be attributed to the elevated solidification temperature. Influenced by crystallization latent heat during the bulk-growth of DNAN， the microstructure of pure DNAN could be demonstrated as columnar blocks while additive-containing counterparts were disclosed as tiny crystallization. Solidified thermodynamic analysis showed that the DNAN solidification enthalpy was positively correlated with the solidification temperature， which is also affected by heterogeneous additive particles on heterogeneous nucleation. The mechanism and verification of the solidification temperature of DNAN in the present paper demonstrated that the additives with NH₄⁺ can significantly improve the solidification temperature of DNAN.

Abstract:To study the mechanical properties of Hydroxyl-Terminated Polybutadience （HTPB） propellant/liner bonding interface for solid rocket motor at different temperatures accurately， the model-Ⅰ fracture properties of the interface were studied with experimental method and simulation. Firstly， the load-displacement curves of the test samples at different temperatures were obtained through uniaxial tensile tests and the failure process of the samples were also recorded with the high-speed cameras. It was found that the failure form of HTPB propellant/liner interface was cohesive failure of HTPB propellant， which indicated that the strength of bonding interface was higher than that of the propellant. From -40 ℃ to 60 ℃， the critical displacement first increased and then decreased， indicating that the effect of temperature on this parameter is obvious. And then a cohesion model with polynomial damage variable was developed， based on the bilinear cohesion law. According to the simulation data， the effects of the interface parameters on the predicted results of the interface properties at different temperatures were analyzed. Moreover， the load-displacement curves of the bonding interface at different temperatures were predicted with the critical displacement as a known parameter. It found that the predicted results by simulation were in agreement with the experimental results， which indicates that the developed interface model can more accurately reflect the temperature-dependent behavior of model-Ⅰfracture of the debonding interface for solid rocket motor than the bilinear cohesion model.

Abstract:Composite solid propellant contains more solid particles， so it is difficult to accurately simulate the extrusion process of the propellant in twin-screw extruder with traditional finite element analysis method. Whereas， the coupling of discrete element method （DEM） and computational fluid dynamics （CFD） is an effective method for simulation the production process of composite solid propellant， but it is very difficult to implement. In this paper， based on the calibrated contact model parameters， the simulation of solid particles in solid propellant with aluminum powder and ammonium perchlorate as main components in twin-screw extrusion process was realized with DEM， and then the DEM-CFD coupling calculation of the solid propellant solid particles and the liquid phase was realized. The results show that the transportation of solid propellant particles in twin-screw calculated by DEM is consistent with the experimental law. Comparing the results between DEM-CFD coupled simulation and DEM for solid particles， it can be seen that the fluidity of materials was significantly improved by adding the liquid phase The filling rate of materials in the screw conveying section increases from 20% to 40%， and the average conveying speed of solid particles increases by 150%， but the stress of screw does not change much.

Abstract:Caged energetic compounds are the hotspots in the research field of energetic materials due to their high energy and density levels， and the clarification of their thermal decomposition mechanisms is significant to the in-depth study of their detonation mechanisms and the improvement of their thermal stabilities. Herein， the thermal decompositions of energetic adamantanes， cubanes and isowurtzitanes are reviewed according to the clue of their caged skeletons， and the thermal decomposition mechanisms of these three caged compounds are also summarized. The thermal decomposition of energetic adamantanes initiated from the substituents and possessed Bridgehead Carbon Effect. In contrast， the thermal decomposition of energetic cubanes and polynitroisowutzitanes usually started from the C—C bond in the cage skeleton and the removal of nitro groups， respectively. Future research should further enrich the types of caged energetic compounds and carry out systematic study on thermal decompositions of caged compounds， especially the thermal decomposition mechanisms of the caged skeletons.

Abstract:The thermites with different morphologies performed differently. To explore the influence of different MoO₃ morphologies on the thermal properties and combustion behavior of Al/MoO₃ thermite， Al/rod-MoO₃ and Al/ribbon-MoO₃ thermite were prepared. Field emission scanning electron microscope （FE-SEM）， X-ray diffractometer （XRD） and differential scanning calorimetry （DSC） were used to characterize their morphology and thermal properties. The DSC results showed that the Al/ribbon-MoO₃ thermite had a heat release about 1702 J·g^-1， while the Al/rod-MoO₃ thermite released 432 J·g^-1. The initial reaction temperature of Al/ribbon-MoO₃ thermite was 401.95 ℃， which was 102.92 ℃ earlier than the 504.87 ℃ of Al/rod-MoO₃ thermite. Non-isothermal thermodynamic analysis showed that the activation energy （E_a） of the two thermites was not significantly different， but the Al/rod-MoO₃ thermite presented a higher thermal explosion critical temperature （T_b）， indicating that the Al/rod-MoO₃ thermite exhibited higher safety. In the open combustion experiment， there was little difference in the combustion behavior of the two thermites. When the thermite burnt out， the Al/ribbon-MoO₃ thermite splashed sparks. The closed-tube combustion experiment showed that the combustion wave velocity of Al/rod-MoO₃ thermite increased primely then decreased， and the maximum wave velocity reached 1037 m·s^-1. The combustion wave velocity of Al/ribbon-MoO₃ thermite was on the rise， and the maximum velocity was 2710 m·s^-1. Al/ribbon-MoO₃ thermite is superior to Al/rod-MoO₃ thermite in heat release and combustion performance， but the Al/rod-MoO₃ thermite is much safer.

Abstract:In order to investigate the thermal decomposition mechanism of the energetic cocrystal TKX-55 and the effect of solvent component dioxane （1，4-dioxane， DIO） on the decay of the energetic component 5，5´-bis（2，4，6-trinitrophenyl）-2，2´-bis（1，3，4-oxadiazole） （BTNPBO）， the molecular dynamics simulations on TKX-55 and pure solvent component DIO were carried out with the ReaxFF-lg （Reactive Force Field-Low Gradients） force field. The results show that the initial decomposition reaction of TKX-55 includes the dimerization of energetic molecules， the hydrogen transfer between energetic and solvent components， the ring-opening reaction of 1，3，4-oxadiazole in energetic components， and the dissociation of nitro group. The dimerization reaction facilitates the rapid growth of the subsequent clusters， and the release of the heat and the stable small molecule products are restricted by the formation of a large number of clusters. It is one essential reason for the high heat resistance of TKX-55. For the pure solvent， the heat release and clustering are constrained at low temperatures； while enhanced at elevated temperatures. The main role of DIO molecules in TKX-55 is thought-to adsorb small reactive intermediates （such as OH， NO， NO₂， etc.） and thereby inhibit the decomposition of BTNPBO.

Abstract:Pentazoles are currently a research hotspot in the field of energetic materials， however， the stability of existing pentazoles is generally not high. In order to develop new pentazoles with better properties， based on the analyses of the available structures， 20 substituted derivatives of HN₅ with the electron-withdrawing groups， i.e.，N₅（CH₂）_x-1R（R=—NO₂，—CF₃，—CN， —CHO， —COOH； x=1， 2， 3， 4）， were designed and studied by using the density functional theory method. The bond dissociation energy （E_BD） of the bonds linked with the N₅ ring and the activation energy （E_a） of the cracking of the N₅ ring were calculated and compared with that of some pentazoles substituted by the electron-donating groups， and the effects of substituents on E_BD and E_a were discussed. Results show that the E_a of all molecules is much smaller than E_BD， indicating that the stability of the N₅ ring is the key factor to determine the stability of the pentazoles. When R is directly connected to the N₅ ring （N₅R）， the E_a of N₅R with R being an electron-withdrawing group is smaller than that of N₅R with R being an H or an electron-donating group. The N₅ ring is a strong electron-withdrawing group， and bearing too much or too little negative charges is not conducive to the stability of the N₅ ring.

Abstract:To investigate the effect of Mg content on the properties of centrifugal atomized aluminum-magnesium （Al-Mg） alloy powders， Al-Mg alloy powders with different mass ratios （70∶30， 50∶50， 30∶70） were prepared by centrifugal atomization. The particle size， morphology， physical phase， and kinetics parameters of the samples were characterized via the particle size distribution meter， scanning electron microscope （SEM）， X-ray powder diffractometer （XRD） and TG-DSC. The effect of different Mg content on the activity of the alloy was also studied by thermal oxidation at 71 ℃. Results showed that all Al-Mg alloy powders had a good size distribution， regular morphology and high sphericity. The metallographic structure demonstrated that Al-Mg30 and Al-Mg50 had a dendritic structure， and Al-Mg70 was composed of α-solid solution and dendritic precipitates. The main phase of the alloy was α-Al， β-Al₃Mg₂ and γ-Al₁₂Mg₁₇. The β-Al₃Mg₂ phase gradually decreased and the γ-Al₁₂Mg₁₇ phase increased with the increasement of Mg content. Moreover， the deactivation rate of Al-Mg alloy powders was found to increase with the increasement of Mg content. The activity of alloy powders remained basically constant after 48 h. The TG-DSC results indicated that both the initial exothermic temperature and the activation energy of the alloys were gradually reduced as the Mg content increased， but the reactive speed was accelerated. The increasement ratio of weight of all Al-Mg alloys was greater than that of micron Mg （53.06%） and Al （8.63%）. The results of Laser ignition showed that the ignition delay of Al-Mg alloy was much shorter than monolithic aluminum， as well as the combustion duration. The microburst phenomenon was observed in the test.

Abstract:To explore the effect of solid boron hydrogen fuel on the burning mechanism of aluminum powder， the simultaneous thermal analysis-infrared mass spectrometry technology and the pyrolysis in-situ cell-Fourier transform infrared spectroscopy technology were employed. Combining with the numerical model of the effect of BHN-12 on the burning reaction of aluminum powder in the explosion flow filed， the mentioned experiment was introduced to study the reaction time， dispersion characteristics and combustion-supporting effect of boron-hydrogen fuel. Results show that the thermal decomposition process of BHN-12 started from 314 ℃， and ended at 360 ℃. There are three exothermic peaks and two endothermic peaks during the decomposition process with a total mass loss 32.3%-33.9%. The decomposition process obeyed the law of power series （Mampel power）， and the dynamic mechanism function is . The gaseous products of the thermal decomposition are mainly H₂， C₂H_4， C₂H₆ and NH₃， and the solid products are simple substances of amorphous C and B. The component transportation model was introduced to simulate the after- burning process of the Al/BHN-12 system. During the process， the dispersion speed of Al fuel was slower than that of BHN-12 particles. At the time of 20 ms， the dispersion radius of Al fuel was about 2.5 m， but it was 3m for BHN-12. In the first 2 ms of the reaction， there was no gaseous product produced， until 4m the gaseous products came out with a temperature 1800 ℃ in the middle of the fire ball. BHN-12 could increase the after-burning temperature of the entire system by about 300 ℃.

Abstract:In order to study the influence of aluminum powder on the mechanical property， interface， combustion， safety， energy， density and other performance of propellants， the glycidyl azide polymer （GAP） propellants with 5%， 10%， 15% and 18% aluminum powder were evaluated by tensile testing machine， dynamic thermomechanical analysis （DMA）， calculation program and etc. Results show that， with the replacement of 320 μm AP with 30 μm aluminum powder and the increase of aluminum powder contents， the propellant has increasing maximal tensile strength and maximal elongation， and improving interface performance. The burning rates change scarcely but the pressure indexes drop down from 0.43 to 0.40 under the pressure of 3-9 MPa. The hazard grades of propellants with 5% and 18% aluminum powder are 1.3 both. The impact and friction sensitivities of propellant with 18% aluminum powder are 0% and 44%， respectively， which are lower than the formulation with 5% aluminum powder （4% and 48%， respectively）. At last， the calculation result shows that with the increase of aluminum powder， the energy and density of propellants grow up， but the standard specific impulse levels off to moderate pace of growth.

Abstract:In order to obtain the metal alloy composite fuel with pressurization effect， Al/Mo/PMF composite powder was prepared by a combination of vacuum suspension smelting， ultra-high temperature gas atomization and mechanical alloying. The phase， morphology and thermal properties of the composite powder were analyzed by XRD， SEM， TG/DTA. The combustion enthalpy and pressurization properties of the composite powder was measured by oxygen bomb calorimeter and constant volume isothermic combustion experiments. Results show that PMF distributes homogeneously in the composite particles after mechanical ball milling， which is helpful to improve the thermal reactivity of the powder and advance the initial reaction temperature. The extra pressurization effect was obvious due to the production of AlF₃ and MoO₃ with low boiling point. The extra pressurization generated by the combustion of Al/Mo/PMF 64/16/20 composite powder was 4.49% higher than that of pure Al powder. With the increase of PMF in the composite， the combustion enthalpy and combustion completeness of the composite powder decreased. The measured combustion enthalpy of Al/Mo/PMF 76/19/5 composite powder was 22541.8 J∙g^-1， while the measured combustion enthalpy of Al/Mo/PMF 64/16/20 composite powder was 16788.5 J∙g^-1. When the PMF content was 5%， the composite can burn completely， meanwhile the extra pressurization can be presented effectively. The corresponding maximum pressure was 3.430 MPa. In addition， the oxidation process and the mechanism of Al/Mo/PMF 76/19/5 composite powder were also studied.

Abstract:In order to study the interface structure of aluminum core/oxide layer intuitively， the slicing method of aluminum powders （2-8 µm） were successfully established based on FIB micro and nano processing technology. The slices were obtained by combining FIB direct cutting with profile thinning. The interface structure of the prepared slice samples was clear and intact， and the oxide layers were not damaged. The microstructure， crystallinity and element distribution of “Al core/oxide layer” under different ageing conditions were obtained were characterized by SEM， HRTEM and EDS. The stoichiometric ratio of Al and O elements in the oxide layer of aluminum particles deviated from the standard Al₂O₃， showing a gradient distribution. The positive correlation between the oxide layer thickness of aluminum particles and the aging temperature has been quantitatively obtained. The oxide layer thickness of the samples without thermal aging was ~5.4 nm， and the oxide layer thickness of the samples aged at 75 ℃ and 95 ℃ increased to （34.1±2.1） nm and （51.3±2.2） nm， respectively.

Abstract:The dispersion characteristics of metal additives in binders might tremendously affect the processing properties of propellants and explosives. Rheological properties of the two metastable intermolecular composites （QAlPV and PAlPV） mixed with hydroxyl-terminated polybutadiene （HTPB）， glycidyl azide polymer （GAP） or poly （ethyleneoxide-co-teterafuran） （PET） separately were investigated by RS-300 rheometer respectively. Results show that all the six sorts of suspensions exhibited pseudoplastic fluid characteristics， and their apparent viscosity decreases with the increase of temperature between 20 ℃ and 60 ℃. In the systems containing GAP and PET， the flow activation energy of the suspensions with PALPV is greater than those containing QALPV. The results present that the suspensions filled with the lamellar aluminum-based composite exhibites more rigidity， meanwhile their apparent viscosity are more sensitive to temperature. Therefore， the dispersion of PALPV in binders could be improved by increasing the temperature. The dispersion and homogeneity of the suspensionsformed by QALPV， GAP or PET separately could be improved by accelerating the shear rate.

Abstract:Aluminum powder was widely used to improve the energy characteristics of explosives and solid propellants due to its excellent properties， such as high activity， high density， high combustion enthalpy and low oxygen consumption. The transition metal Cu had a good catalytic effect on the combustion of aluminum powder and could make the aluminum powder burn more completely. As a binder component of solid propellant， hydroxy-terminated polybutadiene （HTPB） was beneficial to prevent the oxidation and agglomeration of aluminum particles， accordingly in favor of the press-packing and curing while uniformly coating on the surface of aluminum particles. Using the copper acetylacetonate as copper source， formaldehyde and hydrazine as reducing agent， HTPB/Cu/μAl composite particles were prepared by one-pot liquid phase reduction. The structure and morphology of the samples were characterized by IR， XRD， SEM and EDS. Meanwhile， the catalytic performance of HTPB/Cu/μAl on the decomposition of AP was studied. The results showed that the reduced Cu particles were scattered on the surface of aluminum particles， and HTPB was evenly coating on the surface of Cu/μAl. In the DSC curve of HTPB/Cu/μAl， the oxidation exothermic peak of transition metal Cu and the decomposition exothermic peak of HTPB appeared simultaneously between 150-350 ℃. However， the coating had almost no effect on the oxidation exothermic peak of micron aluminum powder at 550 ℃. The average activation energy of HTPB/Cu/μAl was 287.2 kJ·mol^-1， which was 36.35 kJ·mol^-1 lower than that of μAl （323.55 kJ·mol^-1）. Both of the decomposition peaks of AP at high temperature and low temperature had changes when HTPB/Cu/μAl composites were added. Compared with pure AP， the exothermic decomposition peak at high temperature of HTPB/Cu/μAl/AP was reduced by 127 ℃， indicating that the HTPB/Cu/μAl composites could promote the thermal decomposition behavior of AP.

Abstract:High performance liquid chromatography （HPLC） has several advantages， such as high sensitivity， good reproducibility， high efficiency， and high automation. HPLC is widely used for purity analysis and quality monitoring of chemical materials. 2，4，8，10-Tetranitrobenzopyrido-1，3a，6，6a-tetraazapentalene （BPTAP） as a new heat-resistant explosive has received wide attentions in recent years. However， there is a lack of HPLC method for BPTAP at present. Thus， we investigated and optimized the chromatographic conditions of separating BPTAP， and established a HPLC method for the analysis of BPTAP purity. The method is based on a Plus C18 column （4.6×150 mm， 5.0 µm） by using the mixture of acetonitrile and water （containing 0.1 mg·mL^-1 ammonium acetate） as the mobile phase. Gradient elution mode was used with the detection wavelength at 230 nm. The retention time of BPTAP is 9.13 min with good resolution of all peaks （greater than 1.90）. The method was further verified， and it is found that BPTAP has a good linear relationship between 0.5 µg·mL^-1 and 200 µg·mL^-1 with correlation coefficient （R²） of 0.9997. The detection limit and quantification limit are 0.02 µg·mL^-1 and 0.07 µg·mL^-1， respectively. In addition， the method was used for the purity analysis of BPTAP after the recrystallization， and it is proved that this method has good performance for the analysis of BPTAP.

Abstract:To improve the energy property and low vulnerability of cast HMX-Al based explosives， high solid -content aluminized PBX were designed by analyzing the influences of Al and HMX contents on detonation properties. A casted PBX GOL-42 of 90% solid content with HTPB/IPDI binder was manufactured by introducing desensitizers and process agents and was optimized by three-grade grain-size distribution. The GOL-42 explosive showed good processing and safety properties. The detonation property， low vulnerability， mechanical property， thermal property and accelerated storage property were measured by their corresponding standard test methods. The results showed that its measured density， detonation velocity， detonation pressure， Gurney coefficient of Φ25 mm cylinder test was 1.782 g·cm^-3， 8251 m·s^-1， 26.9 GPa， 2.76 mm·μs^-1， respectively. And in the low vulnerability examinations， including bullet impact test， slow cook-off test and fast cook-off test， all the reaction grades were combustion. Its estimated storage life was over 20 years. GOL-42 showed perfect overall properties and was predicted as a long-life low vulnerability cast explosive.

Abstract:With extrusion deposition technology as the core， based on the features of high viscosity and no-resistant to high temperature for propellant， the extrusion deposition rapid prototyping system for propellant was designed and a complete prototype was built. Using a certain ZY propellant as raw material， different materials with concentrations of 27.3%， 33.3%， 38.5%， 42.9%， 46.7% and 50% were prepared. Through 3D printing extrusion experiments， it is found that there is a polynomial function relationship between the inner diameter of the needle and the material concentration. The filling speed range is 2-4 mm·s^-1， the filling rate range is 70%-90%， and the temperature range of the bottom plate is 25-45 ℃. On this basis， the propellant 3D printer was used to print the propellant， and the compression test was carried out. The results showed that the compression strength of the propellant could reach up to 230 MPa.

Abstract:In order to further improve the compactness of energetic powder materials， an ultrasonic-assisted isostatic pressing method is proposed， and an experimental prototype is designed and produced. The simulation software COMSOL is used to analyze the sound field of a single ultrasonic vibrator and the whole isostatic ultrasonic assisted molding system， and the influence of the cover thickness， 10 MPa pre-pressure and ultrasonic power voltage amplitude on the sound field distribution is studied. The simulation results show the rationality and feasibility of the ultrasonic-assisted isostatic pressing. The press molding experiments of polymer-bonded explosive（PBX） simulants are carried out whether to consider ultrasonic-assisted and 10 MPa pre-pressure conditions. The computed tomography（CT） and scanning electron microscope（SEM） are used to test and analyze the samples. The results show that the internal uniformity and compactness of the materials with ultrasonic-assisted and 10 MPa pre-pressure are better than those materials without， and their internal grains are finer and the grain distribution is more uniform.

Abstract:The accommodation of liquid propellant in current-used weapons and equipment makes it important for expanding its application field in various existing weapon systems in the form of general solid propellant. In the current paper， a nitrocellulose-based energetic hollow spherical shell that can be used to encapsulate the liquid propellant is designed. The preparation method is based on the spherical propellant prepared by the internal solution method and on the principle of double emulsification， using W/O type Pickering emulsifier active calcium phosphate and O/W type emulsifier sodium carboxymethyl cellulose to make the emulsion containing nitrocellulose emulsify into a monodisperse W/O/W type emulsion， then evaporate the solvent to obtain the shell. The feasibility of activated calcium phosphate on the W/O type emulsifier has been examined through triple contact angle technique using a contact angle meter. Besides， the basic morphology and particle size， as well as packing density have been characterized using a ultra-depth-of-field electron microscopy system and mass-volume method， respectively. Results show that the three-phase contact angle of activated calcium phosphate is 121.80°. The shell has a large cavity structure with a particle size of 0.7-1.1 mm and a bulk density of 0.1-0.2 g·mL^-1. The microstructure demonstrated a majority of white fiber structure. In addition， embedded white particles in the fiber could also been observed. The optimized ratio of sodium carboxymethyl cellulose to active calcium phosphate， and active calcium phosphate to nitrocellulose should be 1∶1-1.25∶1 and 0.16∶1-0.24∶1， respectively.

Abstract:In order to improve the efficiency of charging and molding of the explosive network， as well as the energy performance， high-energy azide binder 3，3-diazide methyl oxetane-tetrahydrofuran copolymer （PBT）， ultraviolet （UV） curing acrylate and hexanitrohexaazaisowurtzitane （CL-20） were selected as bonding system and main explosive respectively， an ultraviolet assisted curing CL-20-based energetic ink was designed， and using a 3D printing device to write. Rheometer， scanning electron microscope （SEM）， X-ray diffractometer （XRD）， and shore durometer were employed to characterize and test the rheological properties， microstructure， crystal form and hardness of the molded composite. Results show that the ink system is stable when the content of CL-20 is 82%. The curing efficiency of ink is fast with UV assisting， and the surface of molded sample is smooth. The hardness is 70 HA. The special height of impact sensitivity of the composite is 20 cm higher than the raw material； the test of detonation performance shows that the detonation wave can transfer 90° corner， and the critical detonation size reaches 0.387 mm when the line width of charge is 1.2 mm.