Search

As one of the main ammunitions for attacking air targets, the fragmentation and shock wave power of grenades are important parts of evaluating damage ability. In order to study the comprehensive power of grenade, grenade simulation ammunition is designed refers to Italy’s Oto Melera 127 mm ammunition. On the basis of experiment, numerical simulation and empirical formula, the fragmentation velocity, fragmentation spatial distribution and shock wave overpressure are analyzed. The experimental results show that,the scattering direction angle of the grenade simulation ammunition is 93.67°, the scattering angle is 65.42°, and the initial velocity of the fragments is 1 451 m/s. The simulation and calculation results show that, for the scattering angle, the deviation between theoretical and experimental values is relatively small, for fragmentation velocity, the error between theoretical calculation and experimental value is less than 20%, for shock wave overpressure, the error of theoretical value, simulation value and experimental value is less than 15%.

The combustion agglomeration of nano-aluminum (nAl) powder leads to incomplete combustion, which seriously hinders its application as metal fuel. In this work, nAl@AlF3 composites were produced by coating nAl with AlF3via a facile chemical deposition method. TEM and SEM analyses indicated that the AlF3 layer was evenly coated on the surface of nAl with a thickness of 4.6–9.1 nm, thereby varying the quantity of AlF3 applied. Experimental results from combustion indicated that the prepared nAl@AlF3 composites exhibit superior combustion efficiency, a higher combustion rate, and reduced combustion agglomeration as compared to raw nAl. Contrary to the widely accepted explanation that volatilization of AlF3 hinders Al combustion agglomeration, we proved that the gas–solid reaction between nAl and AlF3 plays an important role in inhibiting the sintering of nAl particles produced. The gaseous intermediate (i.e., AlOF and HF) released from the hydrolysis of AlF3 could reduce the diffusion barrier of Al2O3 to facilitate the reaction of Al core, which enhances the combustion reaction kinetics. More importantly, these gaseous products actively participate in the reaction cycle to continuously exert their catalytic effects. [ABSTRACT FROM AUTHOR]

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]

Aluminum hydride (AlH3), as a potential new metal fuel, has attracted extensive attention in the field of hydrogen storage materials, propellants and energetic materials due to its excellent properties. In this paper, a new organic liquid phase reduction method was used to prepare AlH3, and the microstructure and composition of the prepared samples were characterized by SEM–EDS, XRD, FT-IR, XPS, etc. The main crystal phase of the prepared AlH3 was α-AlH3, with high quality and no other impurities. The thermal decomposition behavior and non-isothermal reaction kinetics of AlH3 were investigated by TG-DSC. The results show that there are three exothermic stages in the heating process of AlH3: dehydrogenation of AlH3, first oxidation of Al, and second oxidation of Al. The activation energy of the dehydrogenation of AlH3 is 77.8675 kJ/mol (Kissinger method) and 81.4862 kJ/mol (Ozawa method), respectively. The morphology evolution of AlH3 particles during the heating process (300–3000 K) was simulated using a reaction kinetics method based on the ReaxFF force field. The response behavior of AlH3 in the instantaneous high-temperature detonation environment was investigated using the high-energy laser-induced shock wave technique. Under the impact of a high-energy laser (1006 mJ), the AlH3 sample undergoes an ultra-fast reaction and generates a large amount of plasma. The expansion of the plasma pushes the surrounding air to form a supersonic shock wave and propagates forward. The shock wave propagation velocity of AlH3 is 690.99 m/s in the range of 2.1–12.35 μs, and the higher the laser energy, the faster the shock wave propagation velocity. This study provides the basis for the application of AlH3. [ABSTRACT FROM AUTHOR]