Energetic Materials Frontiers最新文献

Modern trends in the development of energetic materials include the various methods of particle surface modification and the widespread use of nanosized powders. Atomic force microscopy (AFM) is a useful, but often overlooked advanced tool for the investigation of surface, subsurface, and interface properties of energetic compounds. This review highlights the diverse applications of AFM, and provides the various methods of AFM to investigate energetic materials, along with sample preparation techniques. We show that AFM has not only the value for imaging the surface, but also the capability to manipulate and perform the real experiments at the nanoscale. It could be a mechanical stimulation of the crystal and observation of the surface changes after it, or the attachment of the energetic crystal to the tipless cantilever, which approaches the polymeric sample to derive the adhesion force between two materials. We anticipate that over time the AFM-based techniques will be used more and more actively in the research of energetic materials and will benefit our better understanding of the processes taking place at interfaces and surfaces of energetic compounds.

To understand the thermal decomposition and combustion characteristics of HMX/aluminum (Al) composites, this study prepared the HMX/Al composites with different Al contents and carried out the thermal decomposition and combustion performance tests of these composites. The thermal analysis results showed that the activation energy of the HMX/Al composites increased from 483.94 ​kJ·mol⁻¹ to 541.60 ​kJ·mol⁻¹ when the Al content increased from 0 to 30 ​wt%. However, the change in the Al content had little effect on the heat flow of the HMX/Al composites. The combustion results showed that the calorific value of HMX/Al-30 composite reached 16,860 ​J·g⁻¹. The flame height and burning intensity gradually increased with an increase in the Al content, and the burning duration of HMX/Al-10, HMX/Al-20, and HMX/Al-30 gradually decreased by 0.21, 0.57 ​ms and 0.91 ​ms, respectively. The results showed that Al powder as metal fuel can control the combustion reactions and energy output of HMX-based explosives.

The identification and analysis of energetic compounds are important technology in the field of national defence and environmental monitoring. However, as the rapid development of high-energy density materials, designing universal detection strategy for energetic compounds and their composites is still challenging. Herein, we construct a suite of AIEgen-based metal-organic frameworks (MOFs) as the sensing “toolkit” for discriminating four types of energetic compounds, including nitroaromatics, nitrogen-rich heterocycles, nitramine and nitroenamine. Through manipulating the structure of linker and coordination patterns of MOFs scaffold, diversified fluorescence responses can be obtained to simultaneously probe the fluorescence quenching and competitive binding abilities of different energetic compounds in aqueous systems. The “toolkit” sensor array with fluorescence pattern recognition could successfully discriminate seven iconic energetic compounds by principal component analysis. Further performance studies show that the heterogenous materials of energetic compounds can be quantitatively analyzed with linear relationship between stoichiometries and principal component values. The composites from different types of energetic compounds are rapidly identified via AIE MOF-based logic operations. The resulting sensing “toolkit” provides a new avenue for designing olfactory-mimic sensing system.

The aggregation of nano-aluminum powder seriously hinders the energy release of aluminized explosives. This study developed a strategy of using the droplet microfluidic technology to prepare HMX/15 ​wt% n-Al/2 ​wt% (NC and F2604) high-energy microspheres and systematically studied the effects of different binders on the morphology (i.e., roundness) and dispersion properties of microspheres. Moreover, it investigated the thermal decomposition, mechanical sensitivity, and combustion performance using TG, differential scanning calorimetry (DSC), and mechanical sensitivity and combustion experiments. Results show that all the prepared microspheres are regular spherical and enjoy excellent dispersion and high packing density. Using NC as a binder offers more advantages, including favorable roundness, angle of repose, and bulk density values, which were found to be 0.921, 27.1°, and 0.723 ​g·cm^-3, respectively. Using fluorine rubber (F2604) as a binder promotes the oxidation of nano-aluminum and delays the decomposition of HMX. Meanwhile, the microsphere structure can effectively reduce the sensitivity, and the use of F2604 as a binder can significantly improve the safety performance. As a result, the obtained aluminum-containing explosives have impact and friction sensitivities of 60 ​J and 220 ​N, respectively. In addition, compared to physically mixed samples, the microsphere samples have significantly improved combustion performance, more intense combustion reactions, and a shorter burning time, all of which are attributed to their uniform structures and the interactions between components. These results indicate that the strategy using the droplet microfluidic technology provides a new method for preparing high quality aluminized explosives efficiently and safely.

Reactive combustion catalysts (RCCs) are emerging materials for the combustion control of ammonium perchlorate (AP)-based propellants owing to their unique ability to control burning rates, high atomic utilization, and high-energy output. This paper reported that the combustion of AP-based propellants can be greatly enhanced by applying vanadium carbide (V₂C) MXene as RCCs because of its combined advantages of unique reactivity and high chemical energy storage. The decomposition of AP in the presence of V₂C MXene involves both direct reaction decomposition and catalytic decomposition. V₂C MXene preferentially reacts with AP as fuel, releasing its chemical energy in the form of heat and forming VO_x/C nanosheets. The VO_x/C nanosheets formed in situ can serve as catalysts to promote thermal decomposition of the remaining AP. Unlike other combustion catalysts, the direct redox reaction between V₂C MXene and AP dominates the decomposition of AP. Compared with other RCCs that mainly work through catalytic decomposition, V₂C MXene exhibits a greatly increased burning rate, a shorter to-steady-state-combustion time, and greater energy release.

The thermal decomposition processes of CL-20 nanoparticle (NP), core-shell structured CL-20@Al NP, and CL-20@AlO NP were studied through reactive molecular dynamics simulations. The results are as follows: (1) the CL-20@Al and CL-20@AlO NPs decomposed earlier than the CL-20 NP; (2) the Al shell experienced the melting-aggregation process and gradually changed from a shell structure to block aluminized clusters; (3) different in the decomposition of the CL-20 NP, N₂ appeared first in the decomposition of the CL-20@Al and CL-20@AlO NPs, indicating that Al changed the initial decomposition process of CL-20; (4) the quantities of NO₂, NO, and CO₂ produced during the decompositions of the CL-20@Al and CL-20@AlO NPs were much lower than those produced during the decomposition of CL-20 NP. This occurred because the Al atoms had high activity at high temperature and attacked these products to produce massive aluminized substances; (5) Al significantly promoted the movement of H and N atoms but impeded that of O and C atoms in the three systems. This study will present fundamental information about the interfacial behaviors of aluminized explosives.