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.

To improve the safety of ammonium nitrate explosives, a one-step method involving the formation of CL-20/TATB/VitonA composite microspheres using spray drying is presented. The crystal morphology, particle size, crystal structure, thermal properties, and sensitivity of raw materials of CL-20 and TATB, CL-20/VitonA particles, and CL-20/TATB/VitonA microspheres were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and impact and friction sensitivity tests. The SEM results show that the prepared CL-20/TATB/VitonA composites with micro-/nanoscale grain size have a good spherical shape. Thermal analysis data show that TATB coating enhances the thermal stability of CL-20/VitonA. The impact and friction sensitivity results show that superior mechanical properties of these composite microspheres could be maintained. Obviously, this approach is an effective desensitization technique to prepare composite microspheres for explosives.

In this study, a novel spray drying-assisted self-assembly (SDAS) technology was proposed to prepare submicron elemental explosives with good morphology, uniform dispersion, and low sensitivity and spherical submicron RDX, HMX, and CL-20 particles without soft agglomeration were fabricated via such a method. Structural characterizations and thermal stability of the composites were systematically studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimeter (DSC). Moreover, safety performance was analyzed by qualitative testing of impact sensitivity and friction sensitivity. The XRD analysis demonstrated that HMX and CL-20 refined by SDAS maintained the crystal structure of β-HMX and ε-CL-20 before and after refinement, whereas the HMX crystal structure after spray recrystallization refinement was transformed from β-HMX to α-HMX. The DSC results indicated that the thermal decomposition peak temperature of the three particles refined by the SDAS technology had a minimum advancement, and the thermal stability of the particles was relatively superior. More importantly, the H50 of the RDX, HMX, and CL-20 refined by this novel method was increased to 48.3 cm, 44.6 cm, and 31.1 cm, and the probability of friction explosion was decreased to 62%, 62%, and 80%, respectively, thus significantly improving the safety performance as compared with the sample refined by spray recrystallization.

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.

1,1-diamino-2,2-dinitroethene (FOX-7) is a novel explosive with low sensitivity and high performance. The compatibility of FOX-7 with nine common energetic materials including hexanitrohexazaisowurtzitane (CL-20), cyclotetramethylenetetranitramine (HMX), cyclotrimethylenetrinitramine (RDX), 3,4-dinitrofurazanfuroxan (DNTF), 3-nitro-1,2,4-triazol-5-one (NTO), hexanitrostilbene (HNS-II), 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105), 2,4,6-triamino-1,3,5-trinitrobenzene (TATB), and 2,4,6-trinitrotoluene (TNT) were tested by differential scanning calorimetry (DSC) and the vacuum stability test (VST) as the thermal technique and X-ray diffractometry (XRD) as a nonthermal technique. DSC measurements showed that the binary systems of FOX-7/CL-20, FOX-7/HMX, FOX-7/NTO, and FOX-7/TNT were compatible in grade of A, the systems of FOX-7 with heat-resistant explosives including HNS-II, LLM-105, and TATB were compatible as well in grade of A-B, and the binary systems of FOX-7/DNTF and FOX-7/RDX had poor compatibility. VST results indicated that FOX-7 was compatible with nine energetic materials. Besides, the compatibility results of the thermal analysis were confirmed by the XRD technique.