High Explosive Performance Research Articles

Effect of elevated initial temperature on the detonation performance of high explosives

For any high explosive (HE), evaluation of detonation performance requires an assessment of two components, namely detonation timing and the energy accumulated by the detonation products. When heated, the HE density can decrease significantly below the ambient pressing density, raising questions about the detonation performance of heated HEs relative to their ambient counterparts. We examine the detonation performance at an elevated initial temperature (75 °C) of a 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) based insensitive HE through new and legacy rate-stick experiments, together with new cylinder test experiments. We compare the results of the heated tests, with HE densities in the range of 1.867–1.876 g/cm3 after heating, both to tests conducted at ambient temperatures (25 °C) and nominal pressing densities (1.890 ± 0.005 g/cm3), and to data on the detonation performance of ambient low-density pressings (1.874 g/cm3). We find that for large charge diameters, the axial detonation speeds for ambient charges are faster than for heated charges, but that for smaller charges, the detonation speeds for the heated charges are larger. Moreover, for smaller charges, the axial detonation speeds for the heated charges are significantly larger than those observed for ambient charges initially pressed to low density, even though the densities of the heated and low-density-pressed charges are similar. Despite the speed differences, we find that the energy contained within the detonation products is comparable in magnitude for the ambient and heated charges.

Study on Energy Output Characteristics of Aluminized Emulsion Explosive

In order to study the energy output characteristics of multi-component explosives mixed with aluminum powder and emulsified explosives, five groups of emulsified explosives containing aluminum with different proportions were used for underwater explosion experiments and overpressure tests in the air. The experimental data show that when the mass fraction of aluminum powder increases from 0% to 40%, the shock wave energy increases from 0.68 kJ·g-1 to 1.22 kJ·g-1, which increases by 79.41%. Bubble energy increased by 135.66% from 2.44 kJ·g-1 to 5.75 kJ·g-1; the total energy of underwater explosion increased by 123.40% from 3.12 kJ·g-1 to 6.97 kJ·g-1. The explosion overpressure in the air increased by 93.66% from 60.794 KPa to 117.734 KPa. Aluminum powder greatly increases the output level of emulsified explosives. Emulsified explosive containing aluminum has the characteristics of high working capacity and high explosive performance.

N2H62+ Energetic Salts: A Promising Strategy for Increasing the Density and Balance Safety and Energy of Explosives

The conflict between energy characteristics and security of explosives makes the synthesis of high-energy and low-sensitivity explosives always a great challenge. N2H6BTO is a high-energy material with higher density and thermal stability than the parent material and acceptable mechanical sensitivity. Three energetic ionic salts, N2H6(AFTO)2, N2H5TzTO, and N2H6(TzTO)2, were prepared by adjusting the reaction ratio of the parent molecule with hydrazine hydrate. Consistent with N2H6BTO, the density of N2H62+ energetic salts is increased compared to the parent molecules. Moreover, N2H62+ energetic salts show excellent thermal stability (Td ≥ 255 °C) and high explosive performance (D ≥ 9037 m·s–1, P ≥ 28.1GPa) and are insensitive (IS ≥ 35 J, FS ≥ 360 N). N2H62+ energetic salt is expected to be an effective and simple strategy to improve the density of energetic materials and adjust the conflict between the energy characteristics and security of explosives.

Synthesis and characterization of 2,6-dinitro-3,7,10-trioxo-2,4,6,8,9,11-hexaaza[3.3.3]propellane as a promising insensitive high energy material

Insensitive munitions (IMs) that suit safety requirements have received much attention to prevent an accidental explosion of the munition by external stimuli. For example, 1,3,5-trinitro-1,3,5-triazinane (RDX), a sensitive legacy explosive material with high explosive performance, is usually used together with insensitive explosives such as 2,4,6-triamino-1,3,5-trinitrobenzene (TATB) in IM formulation to fit the safe operational range of sensitivities. In recent decades, the development of new high energy materials (HEMs) with remarkable insensitivities have become a forefront topic of the energetic material field. Herein, we report a novel HEM based on a hexaaza[3.3.3]propellane skeleton, 2,6-dinitro-3,7,10-trioxo-2,4,6,8,9,11-hexaaza[3.3.3]pro-pellane (5), which was determined to have high explosive performance along with reduced sensitivity to external stimuli. Both the measured explosive performances and the impact sensitivity of 5 were better than those of TATB. We propose 5 as a promising insensitive HEM and a potential candidate for IM.

Nitro-based and nitro-free tri-cationic azole salts: a unique class of energetic green tri-ionic salts obtained from the reaction with nitrogen-rich bases

Nitrogen-rich heterocycles are essential for designing novel energetic green materials with the combination of high explosive performance and acceptable mechanical sensitivities.

Using thermochemical code EXPLO5 to predict the performance parameters of explosives

Thanks to the development of more powerful computers and efficient numerical techniques, numerical modelling has become a compulsory tool in solving various problems in the field of energetic materials. In cases where measuring techniques are still unable to measure a given parameter, numerical modelling may be the only option of obtaining a value. In addition, numerical modelling helps us to better understand some phenomena, particularly in understanding the influence of input parameters on output results, as well as saving time and money. The thermochemical equilibrium code EXPLO5 is such a tool which enables theoretical prediction of performance of high explosives, propellants and pyrotechnic compositions. The code is used by more than 80 research laboratories worldwide.

On the Question of the Energetic Performance of TKX‐50

AbstractAn analysis of the experimental data available to date shows that the explosive TKX‐50 has really high explosive performance characteristics, although not as outstanding as claimed previously, due to the overestimation of the enthalpy of formation. The obtained experimental data on the dependence of the detonation velocity on the density of TKX‐50 samples agree with the results of calculations, in which the experimentally determined enthalpy of formation 194.1 kJ mol−1 is used. The energetic performance of TKX‐50 surpasses the parameters of nitramines RDX, HMX, and even CL‐20, determined at the same densities. However, the calculated detonation velocity of TKX‐50 at theoretical maximum density is 9287 m s−1, which is slightly lower than the detonation velocity of CL‐20 at maximum density. It is worth noting that the detonation velocity of the TKX‐50 at the experimentally attainable density (1.8 g cm−3) is 9037 m s−1. Calculations using the experimentally determined enthalpy of formation show that high‐energy composite propellant formulations containing TKX‐50 are inferior in a specific impulse to compositions based on CL‐20 and HMX.

Linking chemical precursors to the synthesis of erythritol tetranitrate

Erythritol tetranitrate (ETN) is a homemade explosive with high explosive performance which can easily be synthesized using widely available chemical precursors. Ascertaining the manner in which ETN is synthesized and being able to trace the ETN back to its precursor materials may aid in the forensic identification. As a proof of concept, seven different types of ETN were synthesized with laboratory grade materials as well as commercially available chemicals from the hardware store and grocery store. The seven different types of solid ETN and the reaction quenches were analyzed using high performance liquid chromatography (HPLC). Partial least squares discriminant analysis (PLS-DA) was used to probe the different classes of ETN and reaction quenches. Several PLS-DA models were produced with the seven different types of ETN and quenches having their own classification, ETN and quenches based on their acid source, and ETN and the quenches based on their nitrate source. Regardless of which classification manner was used, there were no differences found between the different types of ETN or their reaction quenches. Moreover, it is demonstrated that there is inherent variability in the synthesis of ETN making HPLC an unreliable method to determine the source of the synthesis materials. Elemental impurities were measured in seven solid ETN samples and their reaction quenches by inductively coupled plasma mass spectrometry (ICP-MS). No differences were found between the solid ETN samples, but there were trace metals found in the reaction quenches which were found to be identifiers of the source material.

On the direct construction of the steady traveling solution to high explosive sandwich, cylinder and aquarium tests via a streamline finite volume approximation

The cylinder, sandwich and aquarium tests are common experiments used to investigate the performance of high explosives. This paper presents a solution technique which simulates these experiments as two dimensional problems in steady traveling coordinates. Using a coordinate system aligned with the streamlines of the flow, an efficient numerical scheme is developed which uses an approximate Riemann solver to model the change in state across streamlines. The technique can also accommodate arbitrary equations of state for the materials. Two verification exercises show that the algorithm converges at second order. Validation studies using the aquarium experiment agreed well with simulations, though the omission of a material strength model leads to some discrepancies between simulation and experiments for the cylinder test. This computational technique is able to predict the behavior of these common high explosive experiments on the order of minutes on a single processor with very fine spatial resolution, on the order of 10 μm.

Bis(dinitropyrazolyl)methanes as Stable High Energy Materials

The development of high energy materials (HEMs) with both high explosive performance and decreased sensitivity is a main theme of current research for energetic materials. Polynitroazoles are good building blocks for new energetic materials because of their stable chemical properties. Two new bis(dinitropyrazolyl)methanes as potential insensitive HEMs were prepared via either the coupling of dinitropyrazole or the nitration of bis(mononitropyrazolyl)methane. Their insensitive properties are also reported and compared to those of RDX (trinitrohexahydro‐s‐triazine) and HNIW (CL‐20, hexanitrohexaazaisowurtzitane).

Theoretical studies of a series of azaoxaisowurtzitane cage compounds with high explosive performance and low sensitivity

Ten novel azaoxaisowurtzitane cage compounds were designed by introducing the oxygen atoms into the azaisowurtzitane cage to replace the N-NO2 groups. Then, their heats of formation (HOFs), energetic properties, strain energies, thermal stability, and impact sensitivity were studied by using density functional theory. The introduction of the oxygen atom in the cage is not helpful for increasing the HOFs, densities, and energetic properties of parent compound CL-20. But all the title compounds exhibit remarkable detonation properties superior to or very close to HMX. All the azaoxaisowurtzitane cage compounds exhibit higher thermal stability than parent compound CL-20. The introduction of the oxygen atom in the cage effectively decreases the sensitivity of parent compound CL-20. Considered the detonation performance, thermal stability, and impact sensitivity, six compounds can be regarded as the potential candidates of HEDC because these azaoxaisowurtzitane cage compounds not only exhibit excellent energetic properties comparable with CL-20, but also have higher thermal stability and lower sensitivity than CL-20.

Furazans with Azo Linkages: Stable CHNO Energetic Materials with High Densities, Highly Energetic Performance, and Low Impact and Friction Sensitivities.

Various highly energetic azofurazan derivatives were synthesized by simple and efficient chemical routes. These nitrogen-rich materials were fully characterized by FTIR spectroscopy, elemental analysis, multinuclear NMR spectroscopy, and high-resolution mass spectrometry. Four of them were further confirmed structurally by single-crystal X-ray diffraction. These compounds exhibit high densities, ranging from 1.62 g cm(-3) up to a remarkably high 2.12 g cm(-3) for nitramine-substituted azofurazan DDAzF (2), which is the highest yet reported for an azofurazan-based CHNO energetic compound and is a consequence of the formation of strong intermolecular hydrogen-bonding networks. From the heats of formation, calculated with Gaussian 09, and the experimentally determined densities, the energetic performances (detonation pressure and velocities) of the materials were ascertained with EXPLO5 v6.02. The results suggest that azofurazan derivatives exhibit excellent detonation properties (detonation pressures of 21.8-46.1 GPa and detonation velocities of 6602-10 114 m s(-1) ) and relatively low impact and friction sensitivities (6.0-80 J and 80-360 N, respectively). In particular, they have low electrostatic spark sensitivities (0.13-1.05 J). These properties, together with their high nitrogen contents, make them potential candidates as mechanically insensitive energetic materials with high-explosive performance.

Analytical Characterization of Erythritol Tetranitrate, an Improvised Explosive.

Erythritol tetranitrate (ETN), an ester of nitric acid and erythritol, is a solid crystalline explosive with high explosive performance. Although it has never been used in any industrial or military application, it has become one of the most prepared and misused improvise explosives. In this study, several analytical techniques were explored to facilitate analysis in forensic laboratories. FTIR and Raman spectrometry measurements expand existing data and bring more detailed assignment of bands through the parallel study of erythritol [(15) N4 ] tetranitrate. In the case of powder diffraction, recently published data were verified, and (1) H, (13) C, and (15) N NMR spectra are discussed in detail. The technique of electrospray ionization tandem mass spectrometry was successfully used for the analysis of ETN. Described methods allow fast, versatile, and reliable detection or analysis of samples containing erythritol tetranitrate in forensic laboratories.

Hot-spot contributions in shocked high explosives from mesoscale ignition models

High explosive performance and sensitivity is strongly related to the mesoscale defect densities. Bracketing the population of mesoscale hot spots that are active in the shocked ignition of explosives is important for the development of predictive reactive flow models. By coupling a multiphysics-capable hydrodynamics code (ale3d) with a chemical kinetics solver (cheetah), we can parametrically analyze different pore sizes undergoing collapse in high pressure shock conditions with evolving physical parameter fields. Implementing first-principles based decomposition kinetics, burning hot spots are monitored, and the regimes of pore sizes that contribute significantly to burnt mass faction and those that survive thermal conduction on the time scales of ignition are elucidated. Comparisons are drawn between the thermal explosion theory and the multiphysics models for the determination of nominal pore sizes that burn significantly during ignition for the explosive 1,3,5-triamino-2,4,6-trinitrobenzene.

Azide Chemistry – An Inorganic Perspective, Part I Metal ­Azides: Overview, General Trends and Recent Developments

AbstractWith Sharpless' and Meldal's discovery of the immensely supportive effect that metal catalysis has on Huisgen's classical 1, 3‐dipolar cycloaddition, azides (RN3) – long underappreciated in organic synthesis – suddenly got in the focus of attention as most crucial players in sensational ‘click chemistry'. Less noisy though with the same commitment and even a much broader scope of scientific topics and objectives, the inorganic azide chemistry has made just as great strides in the last few decades. This review (Part I) gives an introductory survey of the most important results, and informs about modern developments and general trends. Particular emphasis is placed on the recent successful approaches to highly unstable homoleptic azido metal complexes of the main group and early transition elements, as well as on the enormous structural versatility caused by the ‘flexidentate' N3–ligand with its unsurpassed bridging capacities. The presentation in this paper of selected compounds and reactions is meant, in a way, as a prelude to the [3+2]‐cycloadditions of metal azides and related species which will be covered in‐depths in Part II. A large part of the comments finally deals with applications in fields such as catalysis, high explosive performance or magnetism of metal compounds containing azide, today certainly one of the most attractive research areas world‐wide.

Metal–Organic Frameworks (MOFs) as Safer, Structurally Reinforced Energetics

Second-generation cobalt and zinc coordination architectures were obtained through efforts to stabilize extremely sensitive and energetic transition-metal hydrazine perchlorate ionic polymers. Partial ligand substitution by the tridentate hydrazinecarboxylate anion afforded polymeric 2D-sheet structures never before observed for energetic materials. Carefully balanced reaction conditions allowed the retention of the noncoordinating perchlorate anion in the presence of a strongly chelating hydrazinecarboxylate ligand. High-quality X-ray single-crystal structure determination revealed that the metal coordination preferences lead to different structural motifs and energetic properties, despite the nearly isoformulaic nature of the two compounds. Energetic tests indicate highly decreased sensitivity and DFT calculations suggest a high explosive performance for these remarkable structures.

1,1′-Azobis(tetrazole): A Highly Energetic Nitrogen-Rich Compound with a N10Chain

The reaction of 1-aminotetrazole with acidic sodium dichloroisocyanurate allowed isolation of 1,1'-azobis(tetrazole). The rare chain of 10 nitrogen atoms in this compound was confirmed by X-ray crystallography, and the physical and explosive properties of the azo compound were characterized. The title compound possesses both exceedingly high explosive performance and sensitivity.

A new computer code to evaluate detonation performance of high explosives and their thermochemical properties, part I

In this paper a new simple user-friendly computer code, in Visual Basic, has been introduced to evaluate detonation performance of high explosives and their thermochemical properties. The code is based on recently developed methods to obtain thermochemical and performance parameters of energetic materials, which can complement the computer outputs of the other thermodynamic chemical equilibrium codes. It can predict various important properties of high explosive including velocity of detonation, detonation pressure, heat of detonation, detonation temperature, Gurney velocity, adiabatic exponent and specific impulse of high explosives. It can also predict detonation performance of aluminized explosives that can have non-ideal behaviors. This code has been validated with well-known and standard explosives and compared the predicted results, where the predictions of desired properties were possible, with outputs of some computer codes. A large amount of data for detonation performance on different classes of explosives from C–NO 2, O–NO 2 and N–NO 2 energetic groups have also been generated and compared with well-known complex code BKW.

World's highest solar plant installs Kyocera modules

In this paper a new simple user-friendly computer code, in Visual Basic, has been introduced to evaluate detonation performance of high explosives and their thermochemical properties. The code is based on recently developed methods to obtain thermochemical and performance parameters of energetic materials, which can complement the computer outputs of the other thermodynamic chemical equilibrium codes. It can predict various important properties of high explosive including velocity of detonation, detonation pressure, heat of detonation, detonation temperature, Gurney velocity, adiabatic exponent and specific impulse of high explosives. It can also predict detonation performance of aluminized explosives that can have non-ideal behaviors. This code has been validated with well-known and standard explosives and compared the predicted results, where the predictions of desired properties were possible, with outputs of some computer codes. A large amount of data for detonation performance on different classes of explosives from C–NO2, O–NO2 and N–NO2 energetic groups have also been generated and compared with well-known complex code BKW.

Propellant performance of organic explosives and their energy output and detonation velocity limits

Methods for determining the propellant performance of high explosives (HEs) are considered. The common and distinguishing features of the techniques of end acceleration of plates and shell expansion are shown. Experimental data on the propellant performance of individual explosives are given. The influence of metal additives on the brisance (propellant performance) and blast effect of explosive compositions is considered. A theoretical method for estimating the propellant performance is proposed, and the propellant performance of hydrogen-free HEs is calculated using experimental data on the enthalpies of formation and densities of single crystals. The energy output and detonation velocity limits of organic HEs are considered and estimated. Promising directions in the investigation of the properties of HEs are considered.