Performance Of Energetic Materials Research Articles

Introduction of an N-Amino Group onto 4-(Tetrazol-5-yl)-5-nitro-1,2,3-triazole: A Strategy for Enhancing the Density and Performance of Energetic Materials

Abstract2-Amino-5-nitro-4-(tetrazol-5-yl)-1,2,3-triazole (HANTT), its corresponding energetic salts and a dimeric azo compound are successfully synthesized. Compared to 5-nitro-4-(tetrazol-5-yl)-1,2,3-triazole (H2NTT), the neutral N-amino compound HANTT exhibits excellent properties in many aspects, including a higher density (ρ = 1.86 g cm–3), a better detonation performance (D v = 8931 m s–1, P = 32.2 GPa) and a higher thermal decomposition temperature (T d = 237 °C). Among the prepared materials, the hydroxylammonium energetic salt exhibits the best detonation performance (D v = 9096 m s–1, P = 32.8 GPa) and an acceptable mechanical sensitivity (IS = 12 J, FS = 144 N). HANTT, the energetic salts and the azo compound are fully characterized by infrared spectroscopy, multinuclear NMR spectroscopy, elemental analysis and differential scanning calorimetry.

Preparation and performance study of sedum multiceps-like biomimetic structure TKX-50 with various particle sizes

Biomimetic structures often endow materials with excellent performance. In order to explore the impact of biomimetic structures on the performance of energetic materials, the sedum multiceps-like bionic structure dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50) was constructed by self-assembly technology, and controllable particle size adjustment was achieved. Moreover, the effects of solvent ratio, solute content, stirring flow field, and temperature on the quality of sedum multiceps-like TKX-50 crystals were explored, and the formation mechanism of sedum multiceps-like TKX-50 crystals was analyzed. Then, the crystal morphology, crystal form and particle size distribution of sedum multiceps-like TKX-50 were characterized, furthermore, the thermal properties and mechanical sensitivity of sedum multiceps-like TKX-50 were emphatically studied. The results showed that the sedum multiceps-like biomimetic structure TKX-50 was assembled from needle shaped or sheet shaped small particle crystals, and the sedum multiceps-like structure did not change the explosive crystal form of TKX-50. What's more, the thermal decomposition activation energy of the prepared sedum multiceps-like TKX-50 crystal was at least 157.30 kJ⋅mol−1 and at most 185.27 kJ⋅mol−1, and the thermal energy was greatly affected by particle size. In addition, the minimum and maximum ultimate impact energy of the sedum multiceps-like TKX-50 crystals are 20 J and 55 J. The ultimate impact energy of the sedum multiceps-like TKX-50 crystal with different particle sizes is higher than that of the raw TKX-50 (15 J). As a consequence, the sedum multiceps-like bionic structure effectively improves the energy release of TKX-50, reduces the impact sensitivity, and improves the uniformity of particle size distribution.

Theoretical insight into different energetic groups on the performance of energetic materials 2,5,7,9-tetranitro-2,5,7,9-tetraazabicyclo[4,3,0]nonane-8-one.

Energetic materials are a class of materials containing explosive groups or containing oxidants and combustibles. The optimization of energetic materials has a significant impact on the development of industry and national defense. For high-energy density compounds (HEDC) that have not been synthesized or are dangerous to experimental operation, it is of guiding significance to predict its energy level, physicochemical properties, and safety through molecular design and theoretical calculation. Cyclic urea nitramine series compounds are a type of energetic compounds with high density and excellent detonation performance. In this study, 2,5,7,9-tetranitro-2,5,7,9-tetraazabicyclo[4,3,0]nonane-8-one (K-56) was used as the parent structure, and 36 energetic derivatives were designed. The effects of introducing single and multiple substituents on the electronic structure, energy gap, heat of formation, detonation performance, thermal stability, thermodynamic parameters, and surface electrostatic potential of K-56 and its derivatives were discussed in detail. The results exhibit the following: (1) the single substitution of -C(NO2)3 (A6) can reduce the detonation velocity of K-56 by 11.9 % and the detonation pressure by 19.8 %, while the double substitution of -C(NO2)3 (B6) can increase the density of K-56 by 11.6 %, the detonation velocity by 10.9 %, and the detonation pressure by 31 %. (2) The heat of formation of K-56 (-110.0 kJ mol-1) increased by 324.18 % and 628.81 %, respectively, proving that -N3 is an extremely effective group to improve HOF. (3) The thermal stability of the derivatives generated by the monosubstitution of the target group on the six-membered ring is better than that of the parent compound. Gaussian16 and Multiwfn 3.8 packages are the software for calculation. In this study, the parent structure K-56 and its derivatives were optimized at the B3LYP/6-311G (d,p) level to obtain the zero point energy and thermal correction data of all compounds. Then the vibration analysis of the optimized structure is carried out to confirm that its configuration is stable. Then the M06-2X-D3/def2-TZVPP basis set is used to calculate the single point energy.

Underwater pressure waves generated by electrical exploding wire ignited energetic materials: Parametric study and formulation optimization

The combination of electrical wire explosion and low sensitivity energetic materials (EMs) is an efficient and practical method to generate controllable strong pressure waves (PWs), which is receiving extensive attentions in dynamic fracturing related applications. In this paper, the performance of a mud-like EM formulated with aluminum thermite and nitromethane is analyzed experimentally and statistically. Aluminum microparticles (Al MPs) of five different size distributions are tested and the −300 mesh Al MPs is identified as the preferred additive. In order to establish the mathematical relationship between the EM formulation and the PW parameters, the measured pressure profile is reconstructed based on the ignition mechanism to enable parameter extraction, and a statistical model is then developed with back-propagation neural network and data augmentation. Based on the model, the influence of EM components on the pressure pulse parameters is summarized and optimal formulations are proposed.

The positive correlation between the dispersion and catalytic performance of Fe2O3 nanoparticles in nano-Fe2O3-ultrafine AP energetic composites supported by solid UV-vis spectroscopy.

Recently, the widespread use of nanocatalytic materials has contributed to an enormous improvement in the performance of energetic materials, especially, highly dispersed nanomaterials. However, the lack of quantitative methods for analyzing the dispersion of nanomaterials limits their further widespread use. Although various techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), etc. are used to analyze the relative dispersion of nanomaterials, it is not possible to quantitatively analyze their dispersion. Therefore, there has been an effort to develop new methods for the quantitative analysis of nanocatalytic materials. Fortunately, we were able to analyze the dispersion of nanocatalytic materials using the difference in their UV absorbance. More importantly, we established the corresponding difference equation to quantify the dispersion of nanocatalytic materials, which is capable of quantifying the dispersion of nano-Fe2O3 in nano-Fe2O3-ultrafine AP composites. The accuracy of the difference equation was verified using a variety of techniques and the desired results were obtained. Based on the above conclusions, the quantitative analysis method for the dispersion of nanomaterials that we established is expected to be widely used and promote the development of energetic materials.

Determination of detonation characteristics by laser-induced plasma spectra and micro-explosion dynamics.

Determination of macroscale detonation parameters of energetic materials (EMs) in a safe and rapid way is highly desirable. However, traditional experimental methods suffer from tedious operation, safety hazards and high cost. Herein, we present a micro-scale approach for high-precision diagnosis of explosion parameters based on radiation spectra and dynamic analysis during the interaction between laser and EMs. The intrinsic natures of micro-explosion dynamics covering nanosecond to millisecond and chemical reactions in laser-induced plasma are revealed, which reveal a tight correlation between micro-detonation and macroscopic detonation based on laser-induced plasma spectra and dynamics combined with statistic ways. As hundreds to thousands of laser pulses ablate on seven typical tetrazole-based high-nitrogen compounds and ten single-compound explosives, macroscale detonation performance can be well estimated with a high-speed and high-accuracy way. Thereby, the detonation pressure and enthalpies of formation can be quantitatively determined by the laser ablation processes for the first time to our knowledge. These results enable us to diagnose the performance of EMs in macroscale domain from microscale domain with small-dose, low-cost and multiple parameters.

Progress and performance of energetic materials: open dataset, tool, and implications for synthesis

The abundant dataset of detonation parameters for energetic materials is reported, empirical and thermodynamic calculation methods are benchmarked, and implications for design of novel promising compounds provided.

Heat‐Resistant Energetic Materials Deriving from Benzopyridotetraazapentalene: Halogen Bonding Effects on the Outcome of Crystal Structure, Thermal Stability and Sensitivity

AbstractHeat‐resistant energetic material (HREM) has shown its broad applications in petroleum and natural gas exploration, aerospace vehicle as well as solid rocket formulations. Benzopyridotetraazapentalene (BPTAP) (d: 1.84 g cm−3, D: 7670 m s−1, IS: 9 J, Td: 366 °C) is a heat‐resistant energetic material, which is more dense and energetic than those of commercial HREM hexanitrosilbene (HNS) (d: 1.74 g cm−3, D: 7612 m s−1, IS: 5 J, Td: 318 °C). However, low solubility in most of commonly‐used solvents has restricted its applications in detonators as nano‐energetic materials. Meanwhile, recognition on this fused organic backbone is still limited. Herein, we report a chlorine‐inclusion strategy and facile approaches to yield three new derivatives of BPTAP. It is notable that compound 6‐a exhibits its high density (1.92 g cm−3), superior thermal stability (Td: 334 °C), high detonation performance (D: 8084 m s−1), comparable sensitivity (IS: 3 J) to that of HNS, surpassing those of commercially‐used highly‐sensitive primary energetic material lead azide (LA). It is interesting that the chlorine‐inclusion in different position of fused benzopyridotetraazapentalene framework has greatly affected their physical properties such as crystal structure, thermal stability and sensitivity. This investigation offers a unique perspective for deeply exploring the relationship between structure and performance of energetic materials.

Regulating safety and energy release of energetic materials by manipulation of molybdenum disulfide phase

Designing advanced component for synergistically achieving the safety performance and energy releasing of widely studied energetic materials (EMs) is of far-reaching significance in composite solid propellants. Herein, molybdenum disulfide with high-active 1T phase (1T-MoS2) was engineered by a phase-manipulation strategy through chemical Li-intercalation from its original state (2H-MoS2). The as-prepared 1T-MoS2 was used for the improved safety and decomposition performances of two typical EMs (ammonium perchlorate: AP and 1,3,5,7-tetranittro-1,3,5,7-tetrazocane: HMX) in propellants. Lubricant 1T-MoS2 endowed considerable advances in safety performance of EMs, with remarkably reduced the impact and friction sensitivity. Besides, fast energy-releasing performance with visibly lower activation energy was realized for AP@1T-MoS2 and HMX@1T-MoS2. In addition, large decomposition heats were simultaneously achieved. Computational studies disclosed this improvement could be attributed to the multi-coupling effect arising from the promoted electron transfer capability, strong affiliations of catalyst/burning products and the abundant actives sites of 1T-MoS2 phase. Our results demonstrate substantial improvements in the synergistical design of safe and fast-decomposed AP and HMX complex for solid propellants.

A comparative study of thermal kinetics and combustion performance of Al/CuO, Al/Fe2O3 and Al/MnO2 nanothermites

The performance of energetic materials is mainly reflected in two aspects, thermal performance and combustion performance. To figure out the differences in reaction performance, in this paper, thermal and combustion properties of Al/CuO, Al/Fe2O3 and Al/MnO2 nanothermites were studied respectively by thermal analysis and fast heating wire experiments. According to the thermal analysis, the exothermic peak temperature points of Al/MnO2, Al/CuO, Al/Fe2O3 nanothermites were 552.1 °C, 563.1 °C and 565.3 °C, respectively, while the sequence of activation energy calculated from low to high was Al/Fe2O3, Al/CuO, Al/MnO2 nanothermites. By the way, the values of Al/CuO and Al/Fe2O3 nanothermites showed little difference in temperature and activation energy. The ignition energy characterized by direct current had little difference among them, and the sequence from low to high was Al/MnO2, Al/Fe2O3, Al/CuO nanothermites, corresponding to 1.169 A, 1.214 A and 1.221 A, respectively. As for burning rate, Al/CuO burnt the fastest clearly while the Al/Fe2O3 burnt the longest. In terms of combustion performance, Al/CuO and Al/MnO2 were basically the same, with little splash of sparks, and the concentrations of combustion energy were better. The combustion phenomenon of Al/Fe2O3 nanothermite was quite unique with a large number of scattered sparks and poor energy concentration. Finally, the intrinsic reasons for above different phenomena of these three nanothermites were analyzed and discussed.

Origins of the Energy and Safety of Energetic Materials and of the Energy & Safety Contradiction

Origins of the Energy and Safety of Energetic Materials and of the Energy & Safety Contradiction

Structural Rearrangement of Energetic Materials under an External Electric Field: A Case Study of Nitromethane.

As a significant stimulus, the external electric field (EEF) can change the decomposition mechanism and energy release of energetic materials (EMs). Hence, understanding the response of EMs to an EEF is greatly meaningful for their safe usage. Herein, the structural arrangement, a crucial factor in the impact sensitivity and detonation performance of EMs, under the EEF ranging from 0.0 to 0.5 V/Å was investigated via molecular dynamics simulation. Nitromethane (NM) was taken as a case study due to the simple structure. The simulation results show that there exists a critical EEF strength between 0.2 and 0.3 V/Å, which can induce the transition of NM molecules from relatively disordered distribution to solidlike ordered and compacted arrangement with a large density. In this ordered structure, NM dipoles are aligned in a head-to-tail pattern parallel to the EEF direction because of the favored dipole-dipole interactions and weak C-H···O hydrogen bonds. As the EEF strength is enhanced, the potential energy and cohesive energy density of the NM system gradually decrease and increase, respectively, indicative of high thermodynamics stability of ordered arrangement. The results reported here also shed light on the potential of the EEF to induce the nucleation and crystallization to explore new polymorphs of EMs.

Enhanced Intermolecular Hydrogen Bonds Facilitating the Highly Dense Packing of Energetic Hydroxylammonium Salts

The energy and performance of energetic materials can be improved by increasing their crystal packing density. Thus, we propose a strategy involving salification with hydroxylammonium cations (HA+) to increase the packing coefficients (PCs) and packing densities of energetic ionic salts (EISs). Structural analyses and theoretical calculations of the observed EISs indicate that the strong intermolecular hydrogen bonds (HBs) between HA+ and anions are primarily responsible for the increase in EIS density. Such strong HBs usually exist in HA+-based energetic salts and rarely in other EISs but are absent in energetic crystals with neutral molecules. Such HBs induce high PCs and relatively high crystal packing densities by compensating for the relatively lower molecular density of HA+ compared with other cations. Moreover, in combination with HBs in common explosives, we find a simple dependence showing that the shorter the strongest HB corresponds to the higher PC, suggesting that the strongest HB can be rega...

Sensitivity and Performance of Energetic Materials

AbstractThis paper provides an overview of the main developments over the past nine years in the study of the sensitivity of energetic materials (EM) to impact, shock, friction, electric spark, laser beams, and heat. Attention is also paid to performance and to its calculation methods. Summaries are provided of the relationships between sensitivity and performance, the best representations for the calculation methods of performance being the volume heat of explosion or the product of crystal density and the square of detonation velocity. On the basis of current knowledge, it is possible to state that a single universal relationship between molecular structure and initiation reactivity does not yet exist. It is confirmed that increasing the explosive strength is usually accompanied by an increase in the sensitivity. In the case of nitramines this rule is totally valid for friction sensitivity, but for impact sensitivity there are exceptions to the rule, and with 1,3,5‐trinitro‐1,3,5‐triazepane, 1,3,5‐trinitro‐1,3,5‐triazinane, β‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane, and the α‐, β‐ and ε‐polymorphs of 2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane the relationship works in the opposite direction. With respect to the QSPR approach there might be reasonably good predictions but it provides little insight into the physics and chemistry involved in the process of initiation.

Evaluation of nanoparticles in the performance of energetic materials

The addition of nanosized metal particles in propulsion systems such as solid and liquid propellants, hybrid propellant and ramjet motors has recently became a major focus of research. Significant increases in the burning velocity and in the specific impulse are some of the advantages of using nano-scale energetic materials in many different types of propulsion systems. Aluminum has been largely employed as a metallic additive in energetic materials, also in a recently new propulsion system (aluminum/ice propulsion, Alice), and some studies show that the advantages of using nanosized aluminum instead of microsized aluminum are facilitating the ignition of the systems and allowing better incorporation of the components in the formulations and improving its homogeneity. Some of the combustion processes that require high pressures and even higher temperatures can occur in moderate conditions due to the increase of the surface area of the reactants, in this case, the metallic additive. Keywords: Nanoparticles, Aluminum, Energetic materials. Avaliacao das nanoparticulas no desempenho de materiais energeticos

1,2,4‐Triazolium and Tetrazolium Picrate Salts: “On the Way” from Nitroaromatic to Azole‐Based Energetic Materials

AbstractA family of energetic salts based on the picrate anion and several azolium cations were synthesized either by new methods or by known literature procedures. The cations of choice were the following: 5‐amino‐1H‐tetrazolium (1), 5‐amino‐1‐methyl‐1H‐tetrazolium (2), 5‐amino‐2‐methyl‐1H‐tetrazolium (3), 5‐amino‐1,4‐dimethyl‐1H‐tetrazolium (4), 5‐amino‐1,3‐dimethyl‐1H‐tetrazolium (5), 1,5‐diamino‐1H‐tetrazolium (6), 1,5‐diamino‐4‐methyl‐1H‐tetrazolium (7), 3,4,5‐triamino‐1,2,4‐triazolium or guanazinium (8) and 3,4,5‐triamino‐1‐methyl‐1,2,4‐triazolium or methylguanazinium (9). A summary of the 15N NMR shifts for all compounds is given, and the proton‐/methyl‐induced shifts (PISs/MISs) are discussed with relation to the crystal structures. Because hydrogen bonding plays an important role in determining the density and thus the performance of energetic materials, the crystal structures are discussed in detail. In addition, tests to assess the impact (i) and friction (f) sensitivities of the compounds and thermal stability measurements (DSC) were also carried out, revealing insensitive compounds (i > 40 J, f > 360 N) with high thermal stabilities (Td >175 °C). The constant volume energies of combustion were determined experimentally by oxygen bomb calorimetry and their validity was checked by quantum chemical calculation (MP2) of electronic energies. The detonation pressures and velocities of 1 (7795 m s–1, 25.6 GPa), 2 (7343 m s–1, 21.2 GPa), 3 (7213 m s–1, 20.4 GPa), 4 (6876 m s–1, 17.8 GPa), 5 (6846 m s–1, 17.6 GPa), 6 (7864 m s–1, 25.4 GPa), 7 (7492 m s–1, 22.1 GPa), 8 (7495 m s–1, 22.5 GPa) and 9 (7162 m s–1, 19.8 GPa) were predicted by use of the EXPLO5 code. Lastly, the ICT code was used to predict the decomposition gases of all salts. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

On the laser ignition and initiation of explosives

Energetic materials are conventionally ignited by the application of heat to some part of an explosive target. This is most often provided by a flame or by electrical heating using a resistive wire. The material responds by thermally heating and starting a burning zone, which spreads out from the ignition point generating gas. In some cases this zone can accelerate (due to the effect of this gas) into a reactive shock wave, termed detonation. Lasers are used in a variety of applications to thermal heat a range of materials, and thus seem an obvious candidate to trigger chemical reaction in energetic ones. A light pulse offers several advantages over an electrical one, since it may be delivered down a path both immune to electrical effects and chemically stable. Thus, the triggering of safety apparatus (such as the firing of bolts on aircraft exits) represents a major thrust in the development of laser–triggered explosive devices. The energy of the pulse may be used in one of two ways to achieve these effects. In the first, the laser is shone directly upon the chemical medium, which absorbs the light at discrete wavelengths. In the second, it is used to vaporize a metallic flyer that is launched to impact on a target creating a high–pressure zone. Either mechanism starts the required reaction. However, when the pulse is delivered directly to the material, detonation is found to proceed immediately with no transition via burning. This makes the process inexplicable using present concepts. This review will address a range of the experiments conducted and theories developed for this novel field. However, it should be emphasized that the fundamental mechanisms remain to be fully explained making the application both academically stimulating as well as industrially important.