In order to enhance the safety of tetramethylene tetranitramine (HMX), a new strategy was developed to uniformly mix the two explosive components (HMX and TKX-50) at the nanoscale using the oil-in-oil emulsion method. The resulting composite material exhibited a micron-sized flower-like spherical structure, and the crystalline structures of the components within the composite remained unchanged. The specific surface area of the composite was 0.687 m(2) g(-1). Compared with physical mixing, its processing performance was improved. The activation energy of HMX and TKX-50 in the composite was reduced by 296.7 kJ mol(-1) and 48.36 kJ mol(-1), respectively, compared with the raw HMX and TKX-50. The impact sensitivity H-50 was increased from 15 cm for the raw HMX to 22.9 cm, and the friction sensitivity explosion probability was reduced from 100 % to 84 %, significantly improving the mechanical safety properties. This method was expected to provide new insights for the desensitization technology of other high-energy explosives as well as the nanoscale mixing technology for explosives.

Aging behavior of pyrotechnic agents is a serious threat to the reliability of the practical application of pyrotechnic products, while multiple environmental factors make it challenging to characterize the aging mechanism of pyrotechnic agents. This paper explored the aging process of LA in four hygrothermal environments with morphology and structure analysis techniques. LA aging underwent three stages: rapid surface reaction with H2O and CO2, interior hydrolysis by H2O, and CO2 reaction with lead oxides. The cavity structures formed during LA's structural evolution reduced its energy density, causing increased energy dissipation under mechanical stimuli and preventing ignition. Further, reactions formed by inert lead compounds resisted electrostatic ignition, leading to agent failure. This comprehensive study provided a solid foundation for understanding the aging behavior of LA in multistress environments, offering valuable insights into its safe storage and handling.

The design of micro-nanostructures has demonstrated significant potential in advancing the development of energetic materials. This approach not only enhances energy release efficiency but also improves safety performance. Here, the micro-nanostructured HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocine)/TATB (1,3,5-Triamino2,4,6-trinitrobenzene) composite microspheres were successfully prepared via the oil-in-oil emulsion method. The emulsion system facilitated the formation of isolated microenvironments within oil droplets, enabling the controlled design of micro-nanostructures. Analysis revealed that recrystallized TATB and HMX were interconnected, forming micro-nanostructured microspheres. The enhanced interfacial contact and reaction area resulted in a significant increase in the composite's apparent activation energy (Ea) from 446.83 kJ center dot mol-1 (pure HMX) to 599.79 kJ center dot mol-1 (HMX/TATB composite). Concurrently, the safety performance improved substantially, with the characteristic drop height (H50) increasing from 25 cm (HMX) and 32.8 cm (the mixture) to 57.1 cm (HMX/TATB composite). Compared to the mixture, the HMX/TATB composite microspheres exhibited significant improvements in both combustion performance and flowability. This study provides a reference for the design and preparation of micro-nanostructured composites.

This paper successfully prepared micron-sized spherical TATB for the first time using the oil-in-oil emulsion method, which can provide new insights for the spherization of other insoluble explosives.

In order to reduce mechanical sensitivity and improve process performance of TKX-50, spherical TKX-50/TATB composite was prepared via the oil-in-oil emulsion method with TKX-50 (Dihydroxylammonium 5,5 '-bistetrazole-1,1 '-diolate) and TATB (1,3,5-triamino-2,4,6-trinitrobenzene) as raw materials. Based on the experimental results, the ideal circumstances for the emulsion to stabilize were obtained. The SEM results of spherical TKX-50/TATB composite exhibited an excellent spherical structure and size distribution. Furthermore, the SEM, XRD, and FT-IR results of spherical TKX-50/TATB composite demonstrated composite effect of the two basic materials was good. Compared to raw TKX-50 and TATB, the activation energies of spherical TKX-50/TATB composite decreased by 32.75 kJ mol(-1) and 33.61 kJ mol(-1), respectively. The TKX-50/TATB physical mixture was compared with spherical TKX-50/TATB composite, which had a higher bulk density and flowability. The impact sensitivity H-50 of spherical TKX-50/TATB composite was 66.1 cm, which was 50.6 cm higher than that of raw TKX-50, and its friction sensitivity was reduced from 32 % to 24 % compared with that of raw TKX-50.

During the process of external work, the energy of the negative oxygen balanced 5,5 '-Bi-tetrazolium-1,1 ' dioxyhydroxylammonium salt (TKX-50) is not fully released, resulting in low energy utilization efficiency and the generation of harmful gases that pollute the environment. Based on this, in order to adjust the oxygen balance of TKX-50, nano TKX-50/AP composites with positive, zero and negative oxygen balance were prepared by emulsion method. The morphology of nano TKX-50/AP composite was similar to that of hedgehog-like spherical-like particles, with many dense pores formed on the surface, and the average particle size was about 30 mu m. During the composite process, part of TKX-50 reacted with AP to form 5,5 '-bistetrazole-1,1 ' dioxidamide (ABTOX). The first thermal decomposition peak temperature of zero-oxygen balance TKX-50/AP composite was 236.0 degrees C, which was slightly reduced compared with that of TKX-50. The second thermal decomposition peak temperature was 275.1 degrees C, which was 22.2 degrees C higher than that of TKX-50. The heat release of zero-oxygen balance TKX-50/AP composite reached 2206 J g-1, which increased by 35.9% compared to TKX-50, and the energy utilization efficiency was also greatly improved. The drop height of 50% explosion probability (H50) of zero-oxygen balance TKX-50/AP composite was 63.5 cm, and the explosion probability of friction sensitivity was 72%. Compared with TKX-50, it increased by 15.1 cm and decreased by 28%, respectively. The results showed that the mechanical safety performance of TKX-50 had been improved. image

To establish the influence of atmospheric and temperature factors on the stability of LA, a combined environmental stress testing device was designed to simulate reaction characteristics. Morphological characterization methods of SEM and FTIR were carried out to explore the changes of crystal structure, as the pyrolysis behavior of LA under the combined environmental stress was investigated by DSC with two isoconversional kinetic methods and thermal safety software (TSS). The research indicates that CO2 and H2O react with LA to generate basic lead carbonate in the air atmosphere, together with the stimulation of thermal stress, the synergistic effect formed microvoids to erode the crystal structure of LA. The microvoid effect reduced the apparent activation energy (Ea) from 156.47 to 29.52 kJ/mol as the order of degradation of thermal stability of LA was Air> N2 > CO2, which demonstrated that CO2 and N2 atmosphere have a particular protective effect for LA storage, transportation, and application. The pyrolysis reaction mechanism model of LA under the combined environment factors testing was the same as the original LA through the calculation of TSS, thereby the findings could contribute to a better understanding of available boundary conditions for LA.

During storage, lead styphnate (LS) is affected by different environmental stresses. Especially, the dual stress of temperature and humidity has a synergistic aging effect, which degrades or even completely loses the performance of LS, thus seriously affecting the firing reliability and even leading to misfire. Based on this, an accelerated aging test on LS exploring the aging behavior at high temperature and high humidity conditions was reported in this study. At extreme conditions of temperature and humidity, the color of LS had faded and gradually became lighter with the aging time. According to scanning electron microscope results, it indicated that due to long-term erosion, the surface of LS became rough, cracks and many small micropore. Some crystals were broken, and a large amount of debris appeared. Notably, the intensity of some main X-ray diffraction characteristic peaks decreased significantly or even disappeared with the aging time. On the one hand, the thermal stability of LS decreased slightly. On the other hand, its sensitivity performance gradually degraded after hygrothermal aging. Particularly, the flame sensitivity of LS decreased gradually with the aging time. In a word, our findings provide relevant evidence for the reliability of LS in storage conditions.

As one of the most used pyrotechnic composites in spacecraft pyrotechnic devices, the reliability of lead styphnate (LS) in a cryogenic environment needs an adaptability evaluation before the deployment of new deep space exploration programs. Nonetheless, there is a limited understanding of the effects of low temperatures on LS. Herein, we have designed cryogenic storage experiments with a low-temperature in-situ methodology to explore the effects of low temperatures on the properties and performance of LS. By comparing the experimental data before, after storage, and at low temperatures, LS exhibited unique characteristics and failure behaviors at low temperatures than at high temperatures. After storage, the impact sensitivity of LS increased sharply due to particle fragmentation, whilst the flame sensitivity of LS decreased significantly at low temperatures. Employing in-situ powder x-ray diffraction (PXRD) characterization and ignition tests, the low-temperature ignition failure of LS is thought to be closely related to the distortion of the crystal structure of LS, resulting in a "structural shutdown" at-80 degrees C. Our study disclosed the properties of LS at low temperatures and provided feasible research methods for other energetic materials, aiming to prevent possible future risks and help to establish test standards at low temperatures.

Herein, nano-Co3O4/C composite catalyst was successfully synthesized by calcination of cobalt alginate (CA) film, which was prepared by ion exchange method. The morphology and structure of the films and calcined samples were characterized. It was found that the thickness of the film produced by Co2+ substituted Na+ was 20 μm, and the surface and side of the film were smooth and uniform. After the calcination of CA film at 400 °C, Co3O4 nanoparticles grown in situ were loaded onto the carbonized alginate skeleton. The results of the thermal analysis showed that the higher the content of catalyst, the more obvious the catalytic effect on AP. Compared with pure AP, the exothermic peak temperature with 3 wt

As one of the most used pyrotechnic composites in spacecraft pyrotechnic devices, the reliability of lead styphnate (LS) in cryogenic environment needs an adaptability evaluation before the deployment of new deep space exploration programs. Nonetheless, there is limited understanding of the effects of low temperatures on LS. Herein, we have designed cryogenic storage experiments with low-temperature in-situ methodology to explore the effects of low temperatures on the properties and performance of LS. By comparing the experimental data before, after storage and at low temperatures, LS exhibited unique characteristics and failure behaviors at low temperatures than at high temperatures. After storage, the impact sensitivity of LS increased sharply due to particle fragmentation, whilst the flame sensitivity of LS decreased significantly at low temperatures. By means of in-situ PXRD characterization and ignition tests, the low temperature ignition failure of LS is thought to be closely related to the distortion of the crystal structure of LS, resulting in a “structural shutdown” at -80°C. Our study disclosed the properties of LS at low temperatures and provided feasible research methods for other energetic materials, aiming to prevent from possible future risks and help establish test standards at low temperatures.

The strong explosiveness, toxicity and environmental pollution of picric acid make its sensitive detection important. Recently, LMOF materials are showing great potential toward efficient detection of PA. However, hindered by the weak connections between LMOFs and analytes, a feasible fluorescence selectivity and sensitivity to desired compounds by constructed LMOFs remain challenging. Herein, we propose a new strategy by using the innate adsorption ability of MOFs. We choose NDC-Zn, a highly stable LMOF with unique pore structures. The topology of ligands can capture PAs specifically inside the pores and the selectivities are further elevated. PET effects are boosted due to longer and closer contact between ligands and trapped PAs, thus higher sensitivity is also achieved. Besides, a fluorescence enhancement at a visible wavelength was found as the concentration of PA increased, suggesting a potential application of naked-eye recognition for PA. NDC-Zn exhibited an outstanding detection sensitivity for PA with a quenching constant of 49657 M-1, as well as distinctive fluorescence quenching among 9 nitro explosives. From DFT calculations, the fluorescence quenching mechanisms such as PET and the complexation between H2NDC and PA were supported.

Cocrystallization integrates the merits of high energy and insensitivity between energetic molecules to obtain energetics with satisfying performance. However, how to obtain supramolecular synthons accurately and rapidly for predicting the structure and property of cocrystal remains a challenging problem. In this research, an efficient systematic search approach to predict CL-20/2,4-DNI cocrystal has been proposed that 2,4-DNI revolves around CL-20 with a stoichiometric ratio of 1:1 in accordance with the specified rules (hydrogen bond length: 2.2–3.0 Å; search radius: 6.5 Å; the number of hydrogen bond: 1–3). Eight possible supramolecular synthons were obtained by combining quantum chemistry with molecular mechanics. Crystal structure prediction indicated that there are four structures in cocrystal, namely P21/c, P212121, Pbca and Pna21, and CL-20/2,4-DNI cocrystal is likely to be P21/c and the corresponding cell parameters are Z = 4, a = 8.28 Å, b = 12.17 Å, c = 20.42 Å, α = 90°, β = 96.94°, γ = 90°, and ρ = 1.9353 g/cm3. To further study the intermolecular interaction of CL-20/2,4-DNI cocrystal, a series of theoretical analyses were employed including intermolecular interaction energy, electrostatic potential (ESP), Density of State (DOS), Hirshfeld surface analysis. The C–H⋯O hydrogen bonds are demonstrated as the predominant driving forces in the cocrystal formation. The mechanical properties and detonation properties of CL-20/2,4-DNI cocrystal implies that the cocrystal shows better ductility and excellent detonation performances (9257 m/s, 39.27 GPa) and can serve as a promising energetic material. Cocrystal structure predicted was compared with the experimental one to verify the accuracy of systematic search approach. There is a less than 8.8% error between experiment and predict results, indicating the systematic search approach has extremely high reliability and accuracy. The systematic search approach can be a new strategy to search supramolecular synthons and identify structures effectively and does have the potential to promote the development of energetic cocrystal by theoretical design.

As newly developed primary explosives, zinc carbohydrazide perchlorate (ZnCP) and cadmium carbohydrazide perchlorate (CdCP) exhibit excellent performances. However, their inherent thermal characteristics and mechanisms are rarely reported, seriously hindering their further applications. Therefore, an effective thermal analysis method is necessary to better evaluate their thermal properties. Based on this, this study aimed to investigate the thermal behavior and gas evolution characteristics of ZnCP and CdCP by a novel thermogravimetric analysis, fourier transform infrared spectroscopy and gas chromatography/mass spectrometry (TG-FTIR-GC/MS) technique. Consequently, the thermogravimetric-derivative weight loss (TG-DTG) curves indicated that ZnCP and CdCP had three mass-loss stages. Kinetic parameters were calculated using Flynn-Wall-Ozawa (FWO) method. The results showed that the average activation energy of ZnCP was higher than that of CdCP. Moreover, the evolved gases were monitored online by FTIR and GC/MS. The results illustrated that the main gaseous products evolved were H2O, CO2, CO, HNCO, HCN, N2O, N2 and NH3, respectively. Finally, we also proposed a possible decomposition pathway of transition metal carbohydrazide perchlorates. In a word, this study provides sufficient evidences for studying thermal behavior and mechanisms of ZnCP and CdCP. Meanwhile, it also provides a promising thermal analysis technique for transition metal carbohydrazide perchlorates in aerospace, military and civilian applications.

Reducing the thermal decomposition temperature of ammonium perchlorate (AP) is of great significance for its application in composite solid propellants. Here, CuO/SiO2 nanocomposites were prepared using wet impregnation method with Cu (CH3COO)2·H2O as copper precursor followed by a calcination process. The structure and morphology of the prepared samples were characterized with the help of scanning electron microscopy (SEM), Xray diffraction (XRD), and Brunauer–Emmett–Teller (BET), respectively. The outcomes revealed the uniform dispersion of CuO were throughout silica aerogels to prevent agglomeration efficiently. Moreover, results from differential scanning calorimeter (DSC) showed that CuO/SiO2 nanocomposites could effectively enhance AP's thermal decomposition since they have large specific surface areas, many active reduction sites, and good adsorption capacity. As expected, the high decomposition temperature of AP was reduced from 418.7°C to 341.8°C when the amount of CuO/SiO2 nanocomposites was 4 wt%. Therefore, silica aerogels were good catalyst supports of CuO for AP's thermal decomposition. It can bring about new potential for application of new materials in high energy as AP‐based catalysts propellants which are solid in nature.

基于溶胶-凝胶法将金属粒子引入高分子链中,冷冻干燥后得到的多孔含金属高分子材料兼具流散性好、比表面积大以及孔隙结构丰富等特点,既可以解决纳米金属催化剂的团聚问题,又能够提供充足的催化活性位点.制备两种纳米级别聚丙烯酸铜(PAA-Cu)和聚丙烯酸铅(PAA-Pb)多孔含金属高分子材料,采用扫描电镜、透射电镜、红外光谱法、热重质谱联用、比表面及孔隙率分析等手段,对PAA-Cu和PAA-Pb进行详细表征;利用热重-红外-气相色谱-质谱四联用,分析PAA-Cu和PAA-Pb对高氯酸铵(AP)热分解的催化效果.结果表明:PAA-Cu使AP的高温分解峰提前了143.1℃,PAA-Pb使AP的高温分解峰提前了73.7℃;碳化后PAA-Cu孔隙率和比表面积增大,Cu及其氧化物在碳骨架结构原位生成且分散均匀,二者共同增加了催化活性物质与AP的接触面积,有助于AP热分解的催化.

To meet demands of composite solid propellants, seeking a promising material as catalyst for the thermal decomposition of ammonium perchlorate (AP) has drawn attention. Herein, a commercially available nano sponge was used as the carbon source and a novel CuxO/carbonized nano sponge (CuxO/CNS) nanocomposite was successfully prepared via a facile precipitation method followed by a calcination process. CuxO/CNS nanocomposite was a simple sponge carbonization combined with CuxO nanoneedles grown directly on the surface of carbonized sponge substrate. Especially, CuxO nanoneedles looked like grass or leaf, dotted with carbon sponge skeleton. To further deeply evaluate the catalytic effect of CuxO/CNS nanocomposite on the thermal decomposition of AP, DSC technique was carried out. As expected, CuxO/CNS nanocomposite exhibited excellent catalytic effect on the thermal decomposition of AP. In a word, this finding provides a new insight into promising application of new catalysts in AP-based solid propellants.

In this study, copper stearate (CS) was investigated as a potential catalyst for the thermal decomposition of ammonium perchlorate (AP). Copper stearate/ammonium perchlorate (CS/AP) shell–core composite was prepared by in situ synthesis and characterized to sample by SEM and EDS, it shows that CS is evenly dispersed on the surface of AP and forms a shell–core structure. Through using DSC and analyzing the thermal decomposition performance of CS/AP composite,the results show that the thermal decomposition temperature of AP decreased with the increase of catalyst content,when catalyst content is 4%, the thermal decomposition temperature of AP goes down 78.4 °C, and its catalytic effect is best. CS/AP shell–core composite provides a fresh idea for the thermal decomposition of AP.

Simultaneous improvement of the safety performance and thermal decomposition properties of ammonium perchlorate (AP) remains a significant challenge. Therefore, based on inspiration from biological materials, we have prepared a novel copper alginate/ammonium perchlorate (Cu-alginate/AP) composite by facile air atomization. The evaluation of the safety performance and thermal decomposition indicates that these properties were significantly improved. In addition, the possible catalytic mechanism of thermal decomposition of AP is proposed herein. It should be noted that Cu-alginate is a three-dimensional network structure and was uniformly coated on the surface and inside of the AP. When the composite is stimulated by external forces, this unique structure plays a buffering role, absorbing energy and greatly improving safety performance. With increasing temperature, the Cu-alginate easily decomposed and renascent Cu-based nanoparticles were generated by in situ growth. These renascent nanoparticles exhibited excellent catalytic activity for the thermal decomposition of AP. As expected, the bio-inspired material can smartly improve both the safety performance and thermal decomposition of AP. Therefore, these findings provide a promising strategy for the development of composite solid propellants.

为了降低高氯酸铵(AP)的热分解温度,基于离子交换原理,通过喷雾法将海藻酸钠(SA)的钠离子与铁钴离子进行交换制备出海藻酸铁钴(FeCo/SA)复合物,经高温煅烧得到铁酸钴@碳(CoFe2 O4@C)复合催化剂;采用XRD、FT-IR、SEM等对CoFe2 O4@C形貌结构进行了表征;将复合催化剂加至AP中,通过DSC法考察了铁钴离子质量比和煅烧温度对AP热分解催化效果的影响.结果表明,通过离子交换,SA转变为FeCo/SA,常温常压下该复合物为无定型结构,煅烧后原位生成纳米铁酸钴(CoFe2 O4)颗粒并负载在碳化后的碳骨架上,有效阻止了纳米CoFe2 O4颗粒的团聚;在煅烧温度分别为300、400和600℃,铁钴离子的质量比为1:2、1:1和2:1时,煅烧产物均为CoFe2 O4@C;其中铁钴离子质量比为2:1的FeCo/SA,经300℃煅烧得到的CoFe2 O4@C使AP的高温分解峰温降低最多达到96.5℃,表明所制备的CoFe2 O4@C复合催化剂能有效降低AP的热分解温度.