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The use of fluorinated binders can enhance the combustion properties of Al in energetic materials. The underlying mechanism is under investigation and a rational strategy in terms of application has yet to be fully developed. In this study, we have investigated the effect of using a fluorine‐modified hydroxy‐terminated polyether (HTPE) binder to cast aluminized propellants and explosives. We have focused on the combustion behavior and energy release characteristics of Al particles with and without the fluorinated binder during propellant combustion and explosive detonation. The propellants combustion process was recorded using a high‐speed camera and an infrared thermometer. The heat of detonation, detonation velocity and thermal stability of the explosives were investigated using a constant temperature calorimeter, an electrometric method and a small‐scale thermal cook‐off test, respectively. The fluorine‐modified HTPE propellant has exhibited a higher flame temperature and greater energy release efficiency than the HTPE propellant. Moreover, the fluorine‐modified HTPE propellant is characterized by smaller particle agglomerates, leading to a reduction in the mass percentage of agglomerates from 73 wt% to 42 wt%. The detonation heat of fluorine‐modified HTPE explosive increases from 75.2 % to 81 %, but the detonation velocity decreased from 7745 m/s to 7622 m/s. In addition, the fluorine‐modified HTPE binder maintained the thermal stability of explosives due to a milder decomposition before thermal runaway. [ABSTRACT FROM AUTHOR]

The non-ideal behavior of aluminized explosives significantly affects the characteristics of underwater explosion shockwaves, rendering the classical model for underwater explosion shockwaves difficult to apply. In this paper, we analyze the underwater explosion shockwave characteristics of a new generation of aluminized explosives and propose a non-ideal explosive underwater explosion shockwave model incorporating a non-ideal explosive shockwave parameter correction function controlled by the Al/O ratio. First, we conducted underwater explosion tank experiments to obtain four groups of Al/O ratios of shockwave parameters of underwater explosion with aluminized explosives and analyzed the effect of the Al/O ratio on them. Subsequently, we calculated the equation of state of aluminized explosives and established a one-dimensional simulation model of underwater explosion. We verified the reliability of the mesh quality and equation of state using the experimental data. Finally, we used the model to calculate the underwater explosion shockwave parameters of aluminized explosives with Al/O ratios of 0.1–1.3. Based on data analysis, we established a calculation model of the pressure peak and energy flow density of the underwater explosion shockwave of aluminized explosives containing non-ideality correction functions. Our results demonstrate that shockwave pressure peak and energy increase and then decrease with an increase in the Al/O ratio, and the non-ideal behavior of aluminized explosives makes the shockwave energy of underwater explosion more sensitive to the Al/O ratio. The proposed model can better predict the experimental results and can be of high practical value as a general structure for underwater explosion shockwave models of other aluminized or metalized explosives. [ABSTRACT FROM AUTHOR]

In this study, the crystal appearance of industrial grade 2,6-diamino-3,5-dinitropyridine (PYX) was mostly needle-shaped or rod-shaped with an average aspect ratio of 3.47 and roundness of 0.47. According to national military standards, the explosion percentage of impact sensitivity s about 40% and friction sensitivity is about 60%. To improve loading density and pressing safety, the solvent–antisolvent method was used to optimize the crystal morphology, i.e., to reduce the aspect ratio and increase the roundness value. Firstly, the solubility of PYX in DMSO, DMF, and NMP was measured by the static differential weight method, and the solubility model was established. The results showed that the Apelblat equation and Van't Hoff equation could be used to clarify the temperature dependence of PYX solubility in a single solvent. Scanning electron microscopy (SEM) was used to characterize the morphology of the recrystallized samples. After recrystallization, the aspect ratio of the samples decreased from 3.47 to 1.19, and roundness increased from 0.47 to 0.86. The morphology was greatly improved, and the particle size decreased. The structures before and after recrystallization were characterized by infrared spectroscopy (IR). The results showed that no chemical structure changes occurred during recrystallization, and the chemical purity was improved by 0.7%. According to the GJB-772A-97 explosion probability method, the mechanical sensitivity of explosives was characterized. After recrystallization, the impact sensitivity of explosives was significantly reduced from 40% to 12%. A differential scanning calorimeter (DSC) was used to study the thermal decomposition. The thermal decomposition temperature peak of the sample after recrystallization was 5 °C higher than that of the raw PYX. The thermal decomposition kinetic parameters of the samples were calculated by AKTS software, and the thermal decomposition process under isothermal conditions was predicted. The results showed that the activation energy (E) of the samples after recrystallization was higher by 37.9~527.6 kJ/mol than raw PYX, so the thermal stability and safety of the recrystallized samples were improved. [ABSTRACT FROM AUTHOR]

To probe the thermal decomposition mechanisms of a novel fluorinated low-melting-point explosive 3,5-difluoro-2,4,6-trinitroanisole (DFTNAN), a comparative study with trinitroanisole (TNAN) was performed under different heating conditions. The thermal decomposition processes and initial reactions were monitored by DSC-TG-FTIR-MS and T-jump-PyGC-MS coupling analyses, respectively. The results show that fluorine decreased the thermal stability of the molecular structure, and the trigger bond was transferred from the ortho-nitro group of the ether to the para-nitro group. The possible reaction pathway of DFTNAN after the initial bond breakage is the rupture of the dissociative nitro group with massive heat release, which induces the ring opening of benzene. Major side reactions include the generation of polycyclic compounds and fluorine atom migration. Fluorine affects the thermal stability and changes the reaction pathway, and fluorinated products appear in the form of fluorocarbons due to the high stability of the C-F bond. [ABSTRACT FROM AUTHOR]

Finding new melt-cast explosives with desired properties to replace 2,4,6-trinitrotoluene (TNT) has been intensely-pursued in recent decades. However, the contradiction among high energy, low mechanical sensitivity and low-melting makes the innovation of insensitive high-energy-density melt-cast explosives an enormous challenge, so the melt-cast explosives of comprehensive properties better than TNT has not been found. Here, we show a new way to design melt-cast insensitive energetic compound by the introduction of C-F into nitroaromatics. This as-synthesized energetic compound exhibits excellent performance with a high-measured density of 1.81 g cm−3, high thermal decomposition temperature (>300°C), high detonation velocity of 8.54 km s−1, appropriate melting point (82°C) and low viscosity(6200 mpa·S), and extremely low mechanical sensitivities (impact sensitivity, >60 J, and friction sensitivity, >360 N), superior to those of current melt-cast explosives, such as TNT and 2,4-dinitroanisole (DNAN). [ABSTRACT FROM AUTHOR]

Abstract: The property of detonation wave propagation in micro‐channel charges is one of the most important research areas in the field of explosives. Based on DSD (Detonation Shock Dynamics) theory and a linear assumption for the streamline deflection angle, this paper proposes a theoretical model for curved detonation wave propagation in cylinder‐type micro‐channel charges within a strong confinement of metal tube. Further, dynamic control equations related to the detonation velocity and charge diameter are deduced, a numerical calculation method of detonation velocity and shock front shape is given, and propagation rules for detonation waves with different diameters are obtained. An experiment was designed to test the detonation velocities for micro‐channel charges with a booster explosive. The results closely agree with calculations, validating the propagation model of curved detonation waves. It was found that the detonation velocity loss and shock front curvature in the central axis decreased with increasing diameter in the calculation range. Moreover, the smaller the diameter, the greater the rate of change. It is also shown that the model is suitable for the prediction of diameter effects in micro‐channel charges, which is of significance for structural design and performance optimization in MEMS initiation systems. [ABSTRACT FROM AUTHOR]

This article presents numerical simulation of underwater explosions using a one-dimensional 'wedge' model of ANSYS-AUTODYN explicit software for nonlinear dynamics, provided by ANSYS Century Dynamics, Inc. (Canonsburg, PA, USA). Through numerical analysis of a typical underwater TNT explosion problems, the effects of the quadratic and linear viscosity on the key phenomenon of this complicated energetic physical process are conducted. The results show that appropriate values exist for these two viscosities to model the process in given mesh sizes. Based on these preliminary simulations, values of quadratic and linear viscosity, 1 and 0.034, 1 and 0.068 are determined for the ranges of scaled distance from 3 to 10 and 1.5 to 3, respectively. Effects of charge depth, charge mass, and mesh density on the shock wave and bubble pulse parameters are performed for four different explosives, 2,4,5-trinitrotoluene (TNT), H-6, pentolite, and pentaerythritol tetranitrate (PETN). All of the results are compared with empirical equations and show that the ANSYS-AUTODYN software can be used to model and capture the major features of underwater explosion phenomena at acceptable accuracy and timesaving. [ABSTRACT FROM AUTHOR]