Ultrafine hexanitrohexaazaisowurtzitane (CL‐20) samples were prepared by a ultrasound‐ and spray‐assisted precipitation method. Raw CL‐20 and ultrafine CL‐20 samples were characterized by SEM, FT‐IR spectroscopy, XRD, and particle size analysis. The impact sensitivity and thermal stability of two CL‐20 samples were also tested and compared. The results indicate that by this recrystallization process, the mean particle size of CL‐20 is 470 nm, and the particle size distribution was in the range from 400–700 nm. The particle morphology is nearly spheric with a smooth surface. Compared with raw CL‐20, the impact sensitivity of the ultrafine sample is significantely reduced and the drop height (H50) is increased from 12.8 to 37.9 cm. The critical explosion temperature of ultrafine CL‐20 decreased from 235.6 to 229.0 °C, which suggests that the thermal stability of ultrafine CL‐20 is lower than that of raw CL‐20.

A new one-step granulation process for preparing high melting explosive-(HMX-) based PBX was developed. HMX/F 2602 microspheres were successfully prepared by using HMX and F 2602 as the main explosive and binder, respectively. The particle morphology, particle size, crystal structure, thermal stability, and impact sensitivity of the as-prepared HMX/F 2602 microspheres were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), laser particle size analyzer, differential scanning calorimetry (DSC), and impact sensitivity test, respectively. The SEM analysis indicated successful coating of F 2602 on the surface of HMX, and the resulting particles are ellipsoidal or spherical with a median particle size of 940 nm; the XRD analysis did not show any change in the crystal structure after the coating and still has -HNX crystal structure; according to the DSC analysis, HMX/F 2602 prepared by the new method has better thermal stability compared to that prepared by the water suspension process. The impact sensitivity of HMX/F 2602 prepared by this one-step granulation process decreased, and its characteristic height H 50 increased from 37.62 to 40.13 cm, thus significantly improving the safety performance. More importantly, this method does not need the freeze-drying process after recrystallization, thus increasing the efficiency by 2 to 3 times.

To improve the safety of ammonium nitrate explosives, the melamine urea-formaldehyde resin (MUF resin) was selected for the preparation of three typical nitramine explosives (cyclotetramethylenetetranitramine, HMX; cryclo-trimethylenetrinitramine, RDX; and hexanitrohexaazaisowurtzitane, CL-20) based green polymer-bonded explosives (GPBXs) via interfacial polymerization. Meanwhile, the corresponding composite particles prepared by physical mixing and drying bath methods were studied and compared. The particle morphology, crystal structure, thermal stability, and safety performance of the resultant composite particles were characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, differential scanning calorimeter (DSC), and impact sensitivity test, respectively. SEM results showed that MUF was successfully coated on the surface of the three explosives, and different composite particles prepared by the same method have their own unique characteristics. Such effect is attributed to the resin’s ability to isolate and buffer external stimuli. It is obvious that the interfacial polymerization is an effective desensitization technique to prepare core-shell composite particles for explosives.Electronic supplementary materialThe online version of this article (10.1186/s11671-018-2803-z) contains supplementary material, which is available to authorized users.

Herein, a green process for preparing nano-HMX, mechanical demulsification shearing (MDS) technology, was developed. Nano-HMX was successfully fabricated via MDS technology without using any chemical reagents, and the fabrication mechanism was proposed. Based on the “fractal theory,” the optimal shearing time for mechanical emulsification was deduced by calculating the fractal dimension of the particle size distribution. The as-prepared nano-HMX was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). And the impact sensitivities of HMX particles were contrastively investigated. The raw HMX had a lower fractal dimension of 1.9273. The ideal shearing time was 7 h. The resultant nano-HMX possessed a particle size distribution ranging from 203.3 nm to 509.1 nm as compared to raw HMX. Nano-HMX particles were dense spherical, maintaining β-HMX crystal form. In addition, they had much lower impact sensitivity. However, the apparent activation energy as well as thermal decomposition temperature of nano-HMX particles was decreased, attributing to the reduced probability for hotspot generation. Especially when the shearing time was 7 h, the activation energy was markedly decreased.

A novel energetic cocrystal predicted to exhibit greater power and lower sensitivity, consisting of 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB) and cyclotetramethylenetetranitramine (HMX) is presented. The TATB/HMX cocrystals were prepared using a compound solvent of [Emim]Ac and DMSO at 80 °C by recrystallization. Structural characterizations and thermal properties of the raw materials and cocrystals were systematically investigated by scanning electron microscopy (SEM), X‐ray diffraction, fourier‐transform infrared spectroscopy, fourier transform raman spectroscopy and differential scanning calorimetry. The SEM results indicated that microparticles are hexagonal in shape and ∼2 μm in size. The formation of cocrystals originates from the N−H⋅⋅⋅O hydrogen bonding between ‐NO2 (HMX) and ‐NH2 (TATB). Naturally, compared to raw HMX, the impact sensitivity of the cocrystals is reduced. The EXPLO5 program showed TATB/HMX with desirable detonation performance.