Showing papers in "Journal of Energetic Materials in 2013"
TL;DR: In this paper, the effect of additives like oxides, cations, inorganic acids, organic compounds, phase-stablized CuO, etc., on the thermal decomposition of ammonium nitrate is discussed.
Abstract: In this review data from the literature on thermal decomposition of ammonium nitrate (AN) and the effect of additives to their thermal decomposition are summarized. The effect of additives like oxides, cations, inorganic acids, organic compounds, phase-stablized CuO, etc., is discussed. The effect of an additive mainly occurs at the exothermic peak of pure AN in a temperature range of 200°C to 140°C.
187 citations
TL;DR: In this article, a successful attempt has been made to prepare nano-ammonium perchlorate using a nonaqueous method by dissolving ammonium per chlorate (AP) in methanol followed by adding the dissolved AP to the hydroxyl-terminated polybutadiene (HTPB), homogenization, and vacuum distillation of the solvent.
Abstract: Nanomaterials are finding applications in explosives and propellant formulations due to their large surface area and high surface energy. This high surface energy is responsible for the low activation energy and increase in burning rate of the composition. Therefore, a successful attempt has been made to prepare nano-ammonium perchlorate using a nonaqueous method by dissolving ammonium perchlorate (AP) in methanol followed by adding the dissolved AP to the hydroxyl-terminated polybutadiene (HTPB), homogenization, and vacuum distillation of the solvent. The nano-AP thus formed was characterized using a NANOPHOX particle size analyzer (Sympatec, Germany), transmission electron microscopy (FEI, Hillsboro, OR), X-ray diffraction (PANalytical B.V., The Netherlands) and scanning electron microscopy (Ikon Analytical Equipment Pvt. Ltd., Mumbai, India) for particle size, purity, and morphology, respectively. The thermal behavior of nano-AP was also studied using differential thermal analysis–thermo gravimetric an...
42 citations
TL;DR: In this paper, the formation mechanism of HMX/NMP cocrystal were carried out in Cambridge serial total energy package (CASTEP) based on dispersion-corrected density functional theory (DFT-D) with a plane wave scheme.
Abstract: 1,3,5,7-Tetranitro-l,3,5,7-tetrazocine (HMX)/N-methyl-2-pyrrolidone (NMP) cocrystal explosive was prepared by a solution evaporation method. This cocrystal explosive crystallized in the trigonal system (space group ), with cell parameters a = 16.605(8) A and c = 31.496(4) A. Theoretical investigations of the formation mechanism of HMX/NMP cocrystal were carried out in Cambridge serial total energy package (CASTEP) based on dispersion-corrected density functional theory (DFT-D) with a plane wave scheme. The exchange-correlation potential was treated with the Perdew-Burke-Ernzerhof function of generalized gradient approximation, and dispersion force was correlated using Grimme's method. The band structure, density of states, projected density of states, and Mulliken populations were calculated at the generalized gradient approximation level. The results showed that the main host–guest interactions in HMX/NMP cocrystal were hydrogen bonds and stacking interactions, which were the same as those analyzed using...
40 citations
TL;DR: In this paper, four transition metal nanoparticles (TMNs) of 3D series (Cu, Co, Ni, and Fe) were prepared by hydrazine reduction of metal chloride in ethylene glycol at 60°C and characterized by X-ray diffraction (XRD).
Abstract: Four transition metal nanoparticles (TMNs) of 3d series (Cu, Co, Ni, and Fe) were prepared by hydrazine reduction of metal chloride in ethylene glycol at 60°C and characterized by X-ray diffraction (XRD). The XRD pattern showed average particle sizes for Cu, Ni, Co, and Fe of 16.7, 40.5, 27.4, and 35.0 nm, respectively. The activity of these TMN accelerants on the thermal decomposition of ammonium perchlorate (AP) was investigated using thermogravimetry (TG), differential scanning calorimetry (DSC), and ignition delay studies. Isothermal TG data were used to evaluate the kinetic parameters by model fitting as well as an isoconversional methods. The activation energy for thermal decomposition of AP was found to be 66.8, 68.7, 78.5, and 85.4 kJmol−1, respectively, for Co, Cu, Ni, and Fe, when they were mixed with AP. Hence, the order of activity was found to be Co > Cu > Ni > Fe. The accelerant effect of nanoparticles of TMNs was found to be better than their respective nano-oxides.
39 citations
TL;DR: The effect of aluminum particle size on the thermal decomposition of 1,3,5-trimethylene trinitramine (RDX) was investigated using differential scanning calorimetry (DSC), thermogravimetry-terriri-gravimetric (TG-DTG), and DSC-TG-mass spectrometry (MS)-Fourier transform infrared (FTIR) spectroscopy, respectively as mentioned in this paper.
Abstract: The effect of aluminum particle size (10.7 µm, 2.6 µm, and 40 nm) on the thermal decomposition of 1,3,5-trimethylene trinitramine (RDX) was investigated using differential scanning calorimetry (DSC), thermogravimetry–derivative thermogravimetry (TG-DTG), and DSC-TG–mass spectrometry (MS)–Fourier transform infrared (FTIR) spectroscopy, respectively. The results showed that the first exothermic peak (512 K) of RDX diminishes gradually with an increase in the nanosize aluminum content and is overcome by the second exothermic peak when the content of nano-Al reaches 30 wt%. The reaction mechanisms demonstrated by the nonisothermal kinetics of RDX in the absence and presence of 30 wt% Al were conformed to the Avrami-Erofeev equations for all of the RDX compositions. The nucleus growth factor for the RDX/40 nm Al mixture was found to be n = 2/3 compared to n = 3/4 for RDX with and without the microsized Al. The MS and FTIR analyses indicated that the thermal decomposition of RDX in the presence of Al nanopowder...
36 citations
TL;DR: The sensitivity of these compositions to mechanical stimuli (friction, impact, and shock wave) were determined, and the thermal stability and compatibility of the components were tested in this paper.
Abstract: Phlegmatized FOX-7 (1,1-diamino-2,2-dinitroethylene, DADNE) and mixtures with cyclotetramethylene tetranitramine (HMX) were prepared and their detonation properties (the detonation velocity, detonation pressure, acceleration ability, and detonation energy) were investigated The sensitivity of these compositions to mechanical stimuli (friction, impact, and shock wave) were determined, and the thermal stability and compatibility of the components were tested This work furthers the investigation into new compositions for low vulnerability ammunition
32 citations
TL;DR: In this paper, a combinative method with three steps was developed to fabricate HNIW (2,4,6,8,10,12-hexanitro-2, 4, 6, 8, 10, 12-hexaazaisowurtziane) nanoexplosives with the gas anti-solvent (GAS) method improved by introducing a gel frame to limit the overgrowth of recrystallized particles.
Abstract: A combinative method with three steps was developed to fabricate HNIW (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtziane) nanoexplosives with the gas anti-solvent (GAS) method improved by introducing a gel frame to limit the overgrowth of recrystallized particles and an acid-assistant to remove the used frame. Forming the mixed gel, by locking the explosive solution into a wet gel whose volume was divided by the networks, was the key for the fabrication. As demonstrated by scanning electron microscopy (SEM) analysis, a log-normal size distribution of nano-HNIW indicated that about 74.4% of the particles had sizes <120 nm and maximum particle size was ∼300 nm. Energy-dispersive X-ray spectroscopy (EDS) and infrared (IR) characterizations showed that the aerogel embedded with nanoexplosive particles was dissolved in hydrochloric acid solution, and the raw ϵ-HNIW was mostly transformed into the α phase (nano-HNIW) during recrystallization. Nano-HNIW exhibited impact and friction sensitivity almost eq...
22 citations
TL;DR: In this paper, a comparison of green light emission from both barium and amorphous boron-based pyrotechnics is described, and the role of combustion products play in determining flame temperature and continuum radiation is also discussed.
Abstract: A comparison of green light emission from both barium- and amorphous boron–based pyrotechnics is described. Emission spectra are shown for both the U.S. Army in-service M125A1 green star cluster formulation and an amorphous boron–potassium nitrate–binder formulation. The main peaks of the emission spectra, average dominant wavelength, and average spectral purity of both formulations are given. The role that combustion products play in determining flame temperature and continuum radiation is also discussed.
21 citations
TL;DR: In this paper, the formation of mild steel (MS) and copper explosively formed projectiles (EFPs) was simulated in AUTODYN using both the Johnson-Cook (JC) and modified Johnson- Cook (JCM) constitutive models.
Abstract: The formation of mild steel (MS) and copper (Cu) explosively formed projectiles (EFPs) was simulated in AUTODYN using both the Johnson-Cook (JC) and modified Johnson-Cook (JCM) constitutive models. The JC model was modified by increasing the hardening constant by 10%. The previously established semi-empirical equations for diameter, length, velocity, and depth of penetration were used to verify the design of the EFP. The length-to-diameter (L/D) ratio of the warhead used in the simulation varied between 1 < L/D < 2. To avoid projectile distortion or breakup for large standoff applications, the design of the EFP warhead was modified to obtain a lower L/D ratio. Simulations from the JC model underestimated the EFP diameter, resulting in an unrealistically elongated projectile. This shortcoming was resolved by employing the JCM model, giving good agreement with the experimental results. The projectile velocity and hole characteristics in 10-mm-thick aluminum target plates were studied for both models. The se...
18 citations
TL;DR: Azo-bridged azole derivatives were designed and investigated in order to find comprehensive relationship between the structure and performance of nitrogen-rich energetic compounds as mentioned in this paper, where density functional theory was used to predict the optimized structures, heat of formation, and detonation properties.
Abstract: Azo-bridged azole derivatives were designed and investigated in order to find comprehensive relationship between the structure and performance of nitrogen-rich energetic compounds. Density functional theory (DFT) was used to predict the optimized structures, heat of formation, and detonation properties. Introduction of the azido group greatly enhances the heat of formation of these derivatives due to the high energy contribution from the -N3 group. The crystal density was predicted by using the DREIDING force field. The nitroazoles show higher densities than amino and azido derivatives and hence better detonation performance. Thermal stability was analyzed using bond dissociation energies of C-NO2, C-NH2, and C-N3 bonds. Nucleus-independent chemical shifts (NICS) were calculated at the ring centers to find the stability via aromaticity. The sensitivity of the designed compounds were predicted on the basis of band gap between the highest occupied molecular orbital and lowest unoccupied molecular orbital. T...
15 citations
TL;DR: In this paper, a process for the preparation of 1,1-diamino-2,2-dinitroethene suitable for scale-up was developed, and the crucial features to allow scalability and enhance the process safety were the improved synthesis of 2-methoxy-2-methylimidazolidine-4,5-dione and its conversion into 2-hydroxy-2.
Abstract: A process for the preparation of 1,1-diamino-2,2-dinitroethene suitable for scale-up was developed. The crucial features to allow scalability and enhance the process safety were the improved synthesis of 2-methoxy-2-methylimidazolidine-4,5-dione and its conversion into 2-hydroxy-2-methylimidazolidine-4,5-dione, which is a new intermediate in the synthesis of 1,1-diamino-2,2-dinitroethene. Its nitration produced 2-(dinitromethylidene)-imidazolidine-4,5-dione, whose hydrolysis into 1,1-diamino-2,2-dinitroethene was further improved. The use of trifluoroacetic acid to remove sulfuric acid prior to hydrolysis is no longer required. The described procedure yields no hazardous intermediates such as dinitromethane or 2-(dinitromethylidene)-5,5-dinitrodihydropyrimidine-4,6(1H,5H)-dione. Thus, the process safety was enhanced in comparison with the commercial production process starting from 2-methylpyrimidine-4,6-dione.
TL;DR: In this article, a mixture of fuming nitric acid and concentrated sulfuric acid was used for the synthesis of 1,4-diformyl-2,3,5,6-tetrahydroxypiperazine reaction.
Abstract: 4,10-Dinitro-2,6,8,12-tetraoxa-4,10-diazatetracyclo[5.5.0.05,903,11]dodecane (TEX) was obtained by nitrolysis of 1,4-diformyl-2,3,5,6-tetrahydroxypiperazine reaction using a mixture of fuming nitric acid and concentrated sulfuric acid. The optimal process temperature was 54–56°C. The yield of the synthesis depends inter alia on the rate the reactants are introduced into the reaction medium and on the time of conditioning of the reaction mixture. A maximal yield of ca. 40% was achieved at the reactant addition time of 2 h and conditioning time of 2 h. None of the other nitrating mixtures examined proved superior to the conventional nitrating mixture. The product was examined by high-performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), and differential scanning calorimetry (DSC) techniques and the results are reported.
TL;DR: In this article, the deformation caused by the rarefaction is taken into account when analytically calculating the LSC jet velocity based on Birkhoff theory, and an analytical calculation of the jet velocity is accomplished in the detonation front, assuming that the entire liner is projecting at the same time.
Abstract: The jet formation process of linear shaped charges (LSCs) heavily depends on the liner behavior before it collapses. The linear behavior includes the physical shape/deformation, material properties, the projection velocity before impact of the liner, etc. Due to the axially propagating detonation front along the charge, the interaction between the liner and detonation products is one of the important factors that controls the jetting process. In this study, the liner deformation (or arc) caused by the rarefaction is taken into account when analytically calculating the LSC jet velocity based on Birkhoff theory. Based on the formation of an arc in the liner, an analytical calculation of the jet velocity is accomplished in the detonation front, assuming that the entire liner is projecting at the same time. The arc of the LSC liner during projection, which was determined by fitting data generated from hydrocode simulations, allows a non-steady jetting profile. The analytical model described herein is compared...
TL;DR: Theoretical studies have been performed on TACOT, its benzofuroxan derivative z-DBBD, and three different isomers of zDBBD as mentioned in this paper, and the corrected absolute and relative total energies of the geometry optimized structures were calculated at the theoretical level of B3LYP/6-31G(d,p).
Abstract: Theoretical studies have been performed on TACOT, its benzofuroxan derivative z-DBBD, and three different isomers of z-DBBD. The corrected absolute and relative total energies of the geometry-optimized structures were calculated at the theoretical level of B3LYP/6-31G(d,p). The bond dissociation energies were correlated with sensitivity. Mulliken electronegativities (χM) and chemical hardness (η) were obtained by employing frontier molecular orbitals at the HF/6-31G(d,p)//B3LYP/6-31G(d,p) theoretical level. Detonation performance analyses for z-DBBD (4,11-dinitro[1,2,5]-oxadiazolo[3,4-e][1,2,5]oxadiazolo[3′,4′:4,5]benzotriazolo-[2,1-a]benzotriazol-6-ium inner salt 1,8-dioxide), its presently considered isomers, and TACOT were performed. The results showed that the performance of all compounds (compounds 1–4) was as good as that of RDX. The power index results showed that z-DBBD and its isomers were better than TACOT, RDX, and HMX. Compounds 1–4 are all reasonable candidates for high-energy-density materia...
TL;DR: In this article, bulk reaction reactive flow equations are used to model homogeneous shock initiation in an attempt to reproduce experimental data of Sheffield and his group, which was possible to reproduce the main features of the shock initiation process, including thermal explosion, superdetonation, input shock o...
Abstract: Shock initiation of homogeneous explosives has been a subject of research since the 1960s, with neat and sensitized nitromethane as the main materials for experiments. A shock initiation model of homogeneous explosives was established in the early 1960s. It involves a thermal explosion event at the shock entrance boundary, which develops into a superdetonation that overtakes the initial shock. In recent years, Sheffield and his group, using accurate experimental tools, were able to observe details of buildup of the superdetonation. There are many papers on modeling shock initiation of heterogeneous explosives, but there are only a few papers on modeling shock initiation of homogeneous explosives. In this article, bulk reaction reactive flow equations are used to model homogeneous shock initiation in an attempt to reproduce experimental data of Sheffield and his group. It was possible to reproduce the main features of the shock initiation process, including thermal explosion, superdetonation, input shock o...
TL;DR: In this article, structure optimization and frequency calculation of six nitro derivatives of 1,3,5-triazepine were performed using a MP2(FULL)/6-311G(d,p) method.
Abstract: Structure optimization and frequency calculation of six nitro derivatives of 1,3,5-triazepine were performed using a MP2(FULL)/6-311G(d,p) method. In order to obtain reliable energy data, single-point energy and subsequently thermodynamic properties of the species considered were calculated at a fairly high level of theory, CCSD(T)/6-311G(d,p). Solid-phase heats of formation and crystal density were determined using an electrostatic potential (ESP) method utilizing wave function analysis-surface analysis suite (WFA-SAS) code. The result shows that all nitro derivatives possess high positive heats of formation that increase with an increase in the number of nitro groups attached to the ring moiety. The crystal density was found to be in the range of 1.67–1.90 g/cm3. Detonation properties of the compounds were estimated using the Kamlet-Jacobs equation. The results showed that detonation velocity (D) and detonation pressure (P) increased with an increase in the number of nitro groups attached at the ring mo...
TL;DR: In this paper, the authors derived the burning rate of 1H-tetrazole and ammonium nitrate mixtures at pressures of 1 −10 MPa and temperatures of 238 −358 K.
Abstract: In this study, based on the observed burning rate of 1H-tetrazole and ammonium nitrate mixtures at pressures of 1–10 MPa and temperatures of 238–358 K, equations expressing the burning rate as a function of pressure and temperature were derived. In general, the calculated burning rates were in good agreement with the observed values.
TL;DR: In this article, seven analogues of a new high-energetic material, 4-amino-3,5-dinitropyrazole (LLM-116), were designed through changing NH2 or NO2 groups on the pyrazole ring of the material.
Abstract: Seven analogues of a new high-energetic material, 4-amino-3,5-dinitropyrazole (LLM-116), were designed through changing NH2 or NO2 groups on the pyrazole ring of LLM-116. Density functional theory studies on LLM-116 and its analogues were performed at the B3LYP/6-31G(d) level. The geometric and electronic structures, natural bond orbital, charge on the nitro group (-QNO2 ), density, detonation properties, and bond dissociation energies (BDEs) of these molecules were investigated and compared with LLM-116. The results showed that molecules E , F , and G had comparable performance with better insensitivity characteristics and might be potential candidates of powerful energetic materials.
TL;DR: In this paper, a new high-energy organic cesium salt, 1-amino-1-hydrazino-2,2-dinitroethylene (Cs(AHDNE), was synthesized by reacting of AHDNE and Cesium chloride in alkali methanol aqueous solution.
Abstract: A new high-energy organic cesium salt, 1-amino-1-hydrazino-2,2-dinitroethylene cesium salt [Cs(AHDNE)], was synthesized by reacting of 1-amino-1-hydrazino-2,2-dinitroethylene (AHDNE) and cesium chloride in alkali methanol aqueous solution. The thermal behavior and nonisothermal decomposition kinetics of Cs(AHDNE) were studied. The kinetic equation obtained is . The self-accelerating decomposition temperature (TSADT) and critical temperature of thermal explosion (Tb) of Cs(AHDNE) are 152.9 and 163.5°C, respectively. The specific heat capacity of Cs(AHDNE) was determined with a micro-differential scanning calorimetry (DSC) method, and the molar heat capacity was 223.62 J mol−1 K−1 at 298.15 K. The adiabatic time to explosion of Cs(AHDNE) was 93.5 s. Cs(AHDNE) has higher thermal stability than AHDNE. Cs(AHDNE) is sensitive to impact and friction.
TL;DR: In this paper, a novel and effective catalytic system containing N-hydroxyphthalimide (NHPI) and FeCl2 was described for the preparation of hexanitrostilbene (HNS) by the dehydrogenation of HNBB under an oxygen atmosphere.
Abstract: A novel and effective catalytic system containing N-hydroxyphthalimide (NHPI) and FeCl2 is described for the preparation of hexanitrostilbene (HNS) by the dehydrogenation of hexanitrobibenzyl (HNBB) under an oxygen atmosphere. The reaction conditions, such as reaction time, and the amount of NHPI were discussed. The efficient and more environmentally friendly method proved to be a better selection when compared to other previous methods, such as Shipp and Kaplan's method [1].
TL;DR: In this article, the authors used the Chapman-Jouguet (CJ) theory to find compositions with optimum detonation properties for both gaseous mixtures and mixed condensed explosive materials.
Abstract: The main objective of this research is to find compositions with optimum detonation properties. The detonation properties were obtained based on the Chapman-Jouguet (CJ) theory. These properties and the amount of mixture components are defined as objective functions and optimization variables, respectively. The present study was performed for both gaseous mixtures and mixed condensed explosive materials. In the former, the equivalence ratio with optimum detonation properties was found and compared with those obtained from the CEA code. It was found that, in gaseous mixtures, the optimum value for different detonation parameters occurred in different equivalence ratios. For amatol, an industrial high explosive, the best properties corresponded to a composition of 10% trinitrotoluene (TNT) and 90% ammonium nitrate (AN), while the current composition, which is widely used, consists of 20% TNT and 80% AN. It was also found that, in two-component mixed explosives, the composition for zero oxygen balance was cl...
TL;DR: In this article, the authors used a manganin piezoresistance measuring method to investigate the detonation growth properties of charges of lead azide at micrometer diameters and density of 80% theoretical mean density.
Abstract: Microelectromechanical system (MEMS) fuzes are an important development for detonator miniaturization, leading to devices often used as input for an explosive train. The output capability of a microdetonator is strongly influenced by detonation growth of the primary explosive. In this article, research made use of a manganin piezoresistance measuring method to investigate the detonation growth properties of charges of lead azide (Pb(N3)2) at micrometer diameters and density of 80% theoretical mean density (TMD). The samples developed for this research were cylindrical charges of lead azide contained in stainless steel capsules 0.9 mm in diameter and 3 mm in height. An electrical igniter was applied to ignite the charges. The fitting curve for detonation pressure versus height of the explosive charge was obtained, revealing that the critical height of the detonation growth in the microcharge was 1.8 mm, and the detonation growth was stable at the height of the charge at 2.4 mm. The maximum detonation press...
TL;DR: In this paper, an ANSYS AUTODYN-2D hydrocode was used to simulate copper EFP penetration, passage, and impact with a target immersed in water.
Abstract: There are many methods that can be used for the clearance of underwater ammunition; for example, sea mines. In all such techniques, the primary aim is to defuse underwater ammunition without detonation. Explosively formed projectiles (EFPs) have great potential to cleanly and safely defuse underwater ammunition. Underwater simulations and experiments were conducted to highlight the use of EFPs for safe destruction of sea mines. The copper liner configuration was used to study the penetration performance of the EFPs in water. ANSYS AUTODYN-2D hydrocode was used to simulate copper EFP penetration, passage, and impact with a target immersed in water. Simulation results were obtained by making use of Lagrangian and Euler formulations. The results indicated that the velocity of an EFP reduces sharply as it enters the water. However, the velocity of an EFP is stable in the later part of its flight through the water. The results further indicated that after covering five cone diameters (CDs) in water, the veloci...
TL;DR: In this paper, density functional theory (DFT) at a B3LYP/6-31G(d,p) theoretical level was applied to find out how the quantum chemical and detonation properties of RDX change if two RDX molecules come together and form these structures.
Abstract: 1,3,5-Trinitroperhydro-1,3,5-triazine (RDX)-based cage and cage-like nitramines in which two RDX molecules are linked to each other via three and two carbon atoms, respectively, have been investigated computationally using density functional theory (DFT) at a B3LYP/6-31G(d,p) theoretical level. The study focused on finding out how the quantum chemical and detonation properties of RDX change if two RDX molecules come together and form these structures. Both considered nitramines exhibited higher heats of formation (calculated via both PM3 and isodesmic methods) and Kamlet-Jacobs detonation performances and were found to be more sensitive than the reference compounds RDX and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX).