High Explosive Compositions Research Articles

TECHNOLOGY AND PROPERTIES OF EXPLOSIVE TGAF COMPOSITIONS ON THE BASIS OF RUSSIAN INVENTIONS

There are presented results of search and analysis of Russian patents on manufacture technology and properties of low-fusible, high-explosive compositions type TGAF containing trotyl, hexogen, aluminum powder and phlegmatizing agent. Such type compositions marked as TGAG-5, TGAF-5 and MS are widely used in Polish Armed Forces in large-sized munitions like aerial bombs, depth charges, sea mines, torpedoes and warheads of missiles. As a results of above search and analysis, there are found five patent descriptions of Russian inventions [1-5] containing several data on the TGAF explosive composi-tions. These data included information pieces on manufacture technology of such explosives, and data on their physical and chemical properties like chemical stability, heat of explosion, ability to do work by explosion products (performance), brisance (Trauzl and Hess tests), sensitivity to mechanical stimuli, i.e. to impact and friction, temperature of the beginning of thermal decomposition and cook-off temperature. Above information and data are of critical importance as it concerns safety of such type munitions during their production, usage and disposal.

Evaluation of small-scale combustion of an insensitive high explosive formulation containing 3-nitro-1,2,4-triazol-5-one (NTO), 2,4-dinitroanisole (DNAN), and 1,3,5-trinitroperhydro-1,3,5-triazine (RDX)

ABSTRACT Energetic materials are often disposed by open-burning or open-detonation as it is a cost-effective and efficient means of destroying explosive material, and often minimizes the need to transport hazardous explosives to treatment facilities. This practice is often scrutinized for the negative environmental impact of the odorous and unsightly toxic gaseous emissions as well as the resulting deposition residues, which often contain unburned energetic materials. With the increasing use of Insensitive High Explosive compositions in munitions, it is essential that the potential environmental impact of their disposal is assessed before their extensive use to prevent the kind of contamination incidents experienced with legacy explosives. Therefore, the aim of this work was to develop a controlled laboratory experiment to identify the gaseous emissions and the energetic material residues that are generated through the combustion of the IHE components 3-nitro-1,2,4-triazol-5-one (NTO), 2,4-dinitroanisole (DNAN), and 1,3,5-trinitroperhydro-1,3,5-triazine (RDX). A sealed vial containing small (mg) quantities of energetic material was heated until the energetic material combusted. Gas chromatography/mass spectrometry (GCMS) was used to calculate the oxygen consumption and to identify the gases that were generated. The solid residues were analyzed by high-performance liquid chromatography (HPLC) to quantify unburned energetic material. Results showed that DNAN was the most resistant to burning, thus leaving significant quantities of unreacted starting material in the vial. An interesting observation for the IHE formulation was that DNAN also inhibited the combustion of NTO and RDX. The gases emitted during the open burning of IHE components and mixtures included CO, CO2, and N2O as expected, but the proportions differed when the components and mixture were compared, reflecting the influence of DNAN on the burning behavior. From our data, we concluded that open-burning DNAN-based formulations is an environmentally unfavorable waste-management practice for the disposal of IHEs mainly due to generation of solid residues as well as unburnt DNAN.

Two-dimensional lanthanide coordination polymer nanosheets for detection of FOX-7.

Despite the recent surge of interest in two-dimensional (2D) inorganic nanosheets derived from photoactive coordination polymers of lanthanide ions having interesting optical properties, research in this area is still in its infancy. Luminescent lanthanide ions, Eu(iii) or/and Tb(iii), as well as a bis-terpyridine ligand (L), were used in this study as the building blocks for the synthesis of the archetypical layered structure of coordination polymers (CPs) (L·Eu/L·Tb). 2D-nanosheets were obtained through exfoliation of the layered precursor of CPs in a suitable solvent system following a sonication-assisted strategy. These nanosheets exhibit lateral sizes on the micrometer scale (0.3–1 μm) and an ultrathin thickness of 2–6.5 nm. 1,1-Diamino-2,2-dinitroethene or FOX-7 is an insensitive high explosive; in a binder mixture, it exhibits a slightly superior detonation velocity of 8870 m s−1 in comparison to RDX. The insensitive nature of FOX-7 makes it a key component for the development of low vulnerable high explosive compositions for further application in weaponry. The growing demand for FOX-7, for use as a suitable replacement of conventional explosives, is of serious concern to human security. Achieving rapid and efficient detection of this unexplored explosive is a challenging task. In the present study, the developed luminescent nanosheets were used for the first time for micromolar level detection of FOX-7 both in solution and in the solid state. A visually distinct color change of the nanosheets from red (L·Eu) and green (L·Tb) to colorless was witnessed upon UV light irradiation during the detection process. Notably, the solid-state detection technique could be exploited for developing a commercial spray kit for quick onsite screening of this important explosive.

Microstructure effects on the detonation velocity of a heterogeneous high-explosive

ABSTRACTAlthough numerous methods exist for the theoretical calculation of detonation parameters of explosives, few thermodynamic-hydrodynamic-based theoretical codes take into account particle size. The basis for their computational analysis is primarily focused on the equation of state of the detonation products, heat of formation, and density of the explosive composition. This study utilized regression analysis to model the relationship between the microstructure characteristics and detonation velocity of a heterogeneous high-explosive composition containing cyclotrimethylene-trinitrmaine (RDX). The principal characteristics examined were the average particle size of RDX, amount of HMX impurity within the RDX particles, method of RDX manufacture, and compositional density. Statistical analysis demonstrated the relevancy of the microstructure influence on the detonation velocity of the developed experimental compositions of 73 wt. % solids and 27 wt. % polyurethane binder. An equation is developed that accurately predicts detonation velocity based on average particle size, density, and manufacturing process for RDX. The model underscores the significance of the relationship between the average particle size and detonation velocity. Compositions containing smaller average particle sizes of RDX generate higher detonation velocities. A 100 micron increase in the average particle size was shown to decrease detonation velocity by 161 m/s for the monomodal polyurethane compositions used in this study. The relevance of using statistical models for selecting characteristics that result in optimum explosive performance is addressed.

Characterization and modeling of the anisotropic damage of a high-explosive composition

Modelling the behaviour of quasi-brittle materials requires dealing with the anisotropic damage evolution induced by the loading direction and the unilateral effect corresponding to the sudden opening/closure of defects. The latter was the cause deficiencies of some constitutive laws as a no continuous stress/strain response or spurious energy dissipation. In this paper, the behaviour of pressed high explosive is experimentally investigated. Evidences of a pre-existing damage, an anisotropic one developing during loading and the unilateral effect are detailed. The framework of the microplane constitutive laws previously proposed in the literature and based on the volumetric–deviatoric–tangential strain projections is used. Damage is introduced in the model and is affected by an “effectiveness” function weighting its influence with the loading direction. The calibration procedure is detailed and a discussion enables highlighting the strengths and weaknesses of the modelling approach.

Temperature dynamics of aluminized cyclotrimethylenetrinitramine fireballs for event classification

The remote sensing and classification of battlespace explosions might be improved by developing optical signatures for the heat released during secondary combustion. To explore this possibility, mid-wave infrared spectra (1800 to 10,000 cm −1 ) from the detonation of aluminized cyclotrimethylenetrinitramine (RDX) have been observed and analyzed. The field detonations of 12 high-explosive compositions of RDX with varying aluminum and liner volumes were remotely observed with a suite of imagers, spectrometers, and radiometers. The evolution of spatially averaged fireball temperatures has been estimated from the infrared spectra. The effective temperatures decay from initial values of 1290 to 1850 K to less than 1000 K during a 1-s interval. Secondary maxima are observed in the temperature profiles, indicating delayed combustion resulting from the mixing of atmospheric oxygen with the detonation products. The heat released in the secondary combustion is well correlated with the high explosive and liner theoretical heats of secondary combustion and exhibits an average efficiency of about 50%. Fireball lofting rates increase by more than 50% for events where the combustion heat release increases by a factor of 2.

The Effect of Binder Systems on Early Aluminum Reaction in Detonations

AbstractThe objective of this study was to determine compositional variables that result in early reaction of aluminum in detonations of pressed high explosive compositions, defined as reaction by 7 volume expansions as measured by 2.54 cm diameter copper cylinder expansion tests. In order to accomplish this in an economical fashion, statistical mixture design of experiments (DOE) was used in conjunction with anaerobic detonation calorimetry. The effect of binder type (e.g. energetic vs. inert), binder content, HMX content, aluminum content, and aluminum particle size was investigated. It was determined an energetic binder must be used to obtain significant aluminum reaction at volume expansions less than 7 V/V0. Aluminum particle size was only a minor factor. Furthermore, the compositional oxygen balance only provides a general indication of which compositions exhibit more aluminum reaction than others.

Application of heat conduction calorimetry to high explosives

This paper describes some thermal analysis experiments conducted on high explosive samples. These employ differential scanning calorimetry to monitor thermal effects at elevated temperatures (around 200 °C) and heat conduction calorimetry to record thermal effects at much lower temperatures (below 100 °C). The work shows that, due to the generally high thermal stability of many high explosive compositions, heat generation rates are very low, if detectable at all, at normal storage temperatures, even when using a very sensitive instrument. The sensitivity and reproducibility of this technique has been investigated in detail by Wilker et al. [S. Wilker, U. Ticmanis, G. Pantel, Detailed investigation of sensitivity and reproducibility of heat flow calorimetry, in: Proceedings of the 11th Symposium on Chemical Problems Connected with the Stability of Explosives, Sweden, 1998] and shown to be capable of recording heat generation rates of less than a microwatt. This allows continuous measurement of decomposition processes in nitrate ester based propellants at temperatures as low as 40 °C. However, the measurement of very low levels of heat generation is difficult, time consuming and therefore expensive. If the assumption is made that the life limiting process is invariably the slow decomposition of the energetic component, this will frequently lead to very long service lifetime predictions. A number of possible complications are identified. Firstly, due to its low detection threshold, a heat conduction calorimeter may detect other reactions which will not lead to failure, but which may still dominate the heat flow signal. Secondly, the true failure process may generate little energy and be overlooked. In view of these considerations, at present it seems unwise to rely on heat conduction microcalorimetry as the only tool for the assessment of the life of high explosive energetic systems. Based on examples of life terminating processes in high explosives during storage and use, it is clear that decomposition of the energetic material is not invariably the cause of system failure. It is also by no means the only reaction that may take place in, and be observed by, a heat conduction calorimeter.

The scientific foundation and efficacy of the use of canines as chemical detectors for explosives

This article reviews the use of dogs as chemical detectors, and the scientific foundation and available information on the reliability of explosive detector dogs, including a comparison with analytical instrumental techniques. Compositions of common military and industrial explosives are described, including relative vapor pressures of common explosives and constituent odor signature chemicals. Examples of active volatile odor signature chemicals from parent explosive chemicals are discussed as well as the need for additional studies. The specific example of odor chemicals from the high explosive composition C-4 studied by solid phase microextraction indicates that the volatile odor chemicals 2-ethyl-1-hexanol and cyclohexanone are available in the headspace; whereas, the active chemical cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX) is not. A detailed comparison between instrumental detection methods and detector dogs shows aspects for which instrumental methods have advantages, a comparable number of aspects for which detector dogs have advantages, as well as additional aspects where there are no clear advantages. Overall, detector dogs still represent the fastest, most versatile, reliable real-time explosive detection device available. Instrumental methods, while they continue to improve, generally suffer from a lack of efficient sampling systems, selectivity problems in the presence of interfering odor chemicals and limited mobility/tracking ability.

Effect of loading conditions and the initial state on the spalling of an octogen-based high explosive

The results of studies on the spalling of an OTK-90 high-explosive composition under impact loading are presented. Specimens 20–105 mm thick were loaded with the impact of 1.0- and 1.6-mm-thick steel plates explosively accelerated up to velocities of 135–380 m/s. The elastoplastic problem was used to numerically calculate the conditions of loading and spalling. The data obtained were used to derive a simple empirical equation relating maximum tensile stress in a spall plane with the stress gradient in a tensile impulse and maximum stress in a shock wave. The stabilization of specimens is shown to lead to a certain reduction in spalling stresses.

Influence of Transverse Air or Inert‐Filled Gaps in HE Charges on the detonation velocity

AbstractGaps 0.8‐mm wide and transverse to the direction of detonation in high‐performance high explosive compositions, such as squeeze cast TNT/HMX (15/85) or pressed HMX/B (97/3), show no measurable time delay, or it must be less than 50 ns. As expected, delay times increase with the gap width. A surprising result, however, is the convex shape of the time delay curves, which begins at a gap width of about 1 mm. The delay time curves from air and plexiglass‐filled gaps resemble one another very much.

Storage Life of an Aluminised HE Composition .

Most high explosive compositions are organic in nature and they tend to undergo slow decomposition during storage under different environmental conditions. The decomposition degrade the molecular stability of the explosive, thereby resulting in reduced performance and service life. The knowledge of decomposition behaviour of the explosive mass determines the storage life of the composition. Hence, change in the chemical stability, sensitivity, mechanical strength and performance are of utmost importance in the prediction of storage life of explosive/ammunitions systems. This paper presents the results on the rate of gas evolution, change in sensitivity, and thermal stability and weight loss of high explosive compositions, viz., Dentex and TNT when exposed to elevated temperature. Based on the collected data, a tentative storage life for the aluminised (Dentex) composition has been computed to be 15 years. The data has been compared with TNT, a standard explosive for assessing the storage life.

Rapid Colorimetric Determination of Phosphorus in High Explosive Compositions Following a Wet-Ashing Procedure

Rapid Colorimetric Determination of Phosphorus in High Explosive Compositions Following a Wet-Ashing Procedure