Possibility of the formation of diamonds as a result of the detonation of picric acid

The dependences of the detonation velocity and electrical resistance on the initial density of picric acid were determined for developing the conclusions made earlier for TNT- and RDX-based comjpositions concerning the effect of diamond formation on the detonation velocity and resistance of detonation products. A discontinuity of the dependence of the detonation velocity on the initial density and an increase of the resistance of the detonation products in the region of this discontinuity, which are related to diamond formation in the detonation wave, were found. The relative position of the dependences of resistance on density and of the discontinuities of the dependences of the detonation velocity on the density for various explosives is discussed.Chernogolovka. Translated from Fizika Goreniya i Vzryva, Vol. 27, No. 4, pp. 117–121, July–August, 1991.     

Comparative brisant characteristics of some classes of industrial emulsion explosives

The four types of mixtures consisting of the two bases (aqueous solutions of ammonium nitrate and ammonium dinitroamide) and the two additions (hollow glass microballoons and gunpowder) are considered in this work. On the base of thermodynamic computations of an ideal detonation and accompanying processes (shock and rarefaction waves) there were obtained not only the dependences of detonation parameters on addition quantities to mixtures, but the pressure versus particle velocity diagrams, too, which in comparison with Hugoniots relatively soft (water) and hard (aluminium) substances allowed to determine values of pressure in the shock waves being produced in surroundings nearby the end-wall and lateral surface of a charge. It is proposed to characterize the brisant effect of an explosive by a value of relative brisance which is calculated as percentage ratio of pressures of shock waves generated in surroundings under the same conditions by detonation products of the given explosive and the standard one. It is shown that the brisant effect of the new emulsion explosives is comparable and even can exceed that of TNT of maximal density. It is shown as well that the brisant ability of industrial emulsion explosives can be raised by 60 and more percents by replacing ammonium nitrate with ammonium dinitroamide and hollow glass microballoons with powders being obtained as a result of military industry conversion and utilization of munitions.     

Preparation and Performances of Castable HTPB/CL‐20 Booster Explosives

HTPB/CL‐20 castable booster explosives were prepared successfully by a cast‐cured process. Scanning electron microscope (SEM) and the charge density test were employed to characterize the molding effect of HTPB/CL‐20 explosives. The propagation reliability, detonation velocity, mechanical sensitivity, thermal decomposition characteristics and thermal stability of the HTPB/CL‐20 explosives were also measured and analyzed. The results show that, when CL‐20 content is less than 91 wt.‐%, the charges with better molding effect were obtained easily. The critical diameter of HTPB/CL‐20 explosives is less than 1 mm, which exhibits good propagation reliability. When the density of HTPB/CL‐20 charge with 91 wt.‐% CL‐20 is 1.73 g cm⁻³, its detonation velocity can reach 8273 m s⁻¹. Moreover, this kind of explosives has low mechanical sensitivity and good thermal stability.     

Experience of using synchrotron radiation for studying detonation processes

Results of studying detonation processes in condensed high explosives, which are obtained by methods based on using synchrotron radiation, are summarized. Beam parameters are given, and elements of the station and measurement system are described. Data on the density distribution in the detonation front for several high explosives are presented, and values of parameters in the Neumann spike and at the Jouguet point are determined. A method used to reconstruct a complete set of gasdynamic characteristics (density fields, particle velocity vector, and pressure) from the experimentally measured dynamics of the x-ray shadow of the examined flow is described. Results of using this method for studying detonation of a charge of plastic-bonded TATB are presented. A method of measuring small-angle x-ray scattering in the course of detonation conversion is described. Based on results obtained by this method for a number of high explosives with an excess content of carbon, kinetics of condensation of free carbon and dynamics of the mean size of nanoparticles being formed thereby are analyzed.     

Nanometric Aluminum in Explosives

Aluminum nanopowders, because of their larger surface area, can increase the burning rate of propellants. It has been suggested that the powders could also enhance the detonation properties of certain explosives. For these reasons, an experimental study was undertaken to compare the performance of nanometric and micrometric aluminum in various explosives. No enhancement of performance was found in plastic‐bonded explosives. In fact, a reduction of the detonation velocity was found in plastic‐bonded explosives that are based on an energetic binder system. No increase of the detonation velocity was found in mixtures of aluminum and either Composition B or Ammonium Nitrate Fuel Oil, but a small increase in the heat of detonation was measured. The mixture of TNT and nano‐aluminum demonstrated higher detonation velocities and heats of detonation. The increase was higher at small charge diameters. Nanometric aluminum was shown to reduce the critical diameter of such mixtures, and it is concluded that the nano‐aluminum reacts faster than regular micron‐size particles in TNT/Al compositions.     

A Simple and Rapid Evaluation of Explosive Performance – The Disc Acceleration Experiment

It is crucial in the development of a new explosive to obtain an evaluation of performance early in the process when the availability of material is limited. Evaluation requires dynamic measurements of detonation velocity, pressure, and expansion energy – typically in separate experiments that require large amounts of material, time, and expense. There is also a need for evaluation of the total available thermodynamic energy. The dynamic evaluations, in particular, have been a major hindrance to development of new explosives. The new experimental testing method to be described here requires small charges and obtains accurate measurement of all three of the detonation performance characteristics in a single test. The design, a Disc Acceleration eXperiment (DAX), provides an initial condition of steady detonation and a charge‐geometry amenable to 2D hydrodynamic simulations. The velocity history of a metal disk attached to the end of the explosive charge is measured with Photonic Doppler Velocimetry (PDV). This disc velocity data is analyzed to give both CJ pressure and expansion energy. The detonation velocity is obtained with probes along the charge length. The experiments and subsequent analyses are concentrated on LX‐16, a known PETN based explosive, for the purpose of establishing the accuracy of the method and to provide a standard for comparison with other explosives. We present details of the experimental design and also detonation velocity and PDV results from a number of experiments. The total available internal energy for the explosive was obtained from published detonation calorimetry measurements by Ornellas [1], and from thermodynamic equilibrium calculations. An equation‐of‐state (EOS) for LX‐16 was derived from hydrodynamic simulations of thin plate‐push velocity‐time data. We will show a successful comparison with a previously published Jones‐Wilkins‐Lee (JWL) EOS for PETN by Green and Lee [2–4].     

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. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 1, pp. 99–111, January–February, 2007.     

Experimental study on the effect of titanium hydride content on the detonation performance of emulsion explosives

In order to improve the explosion characteristics of emulsion explosives, titanium hydride was added to emulsion explosives to produce a new type of hydrogen storage emulsion explosives. Charges with different contents of titanium hydride were evaluated through underwater explosion experiments and detonation velocity tests. The tests on underwater explosion and detonation velocity reveal that compared to pure emulsion explosives, the detonation parameters of emulsion explosives containing titanium hydride showed a trend of first increasing and then decreasing. When the mass ratio of titanium hydride in the emulsion explosive is 1 % to 3 %, all detonation parameters have been improved to a certain extent. When the mass ratio of titanium hydride in the emulsion explosive is 3 % to 10 %, only part of the detonation parameters (specific impulse, specific shock energy, specific total energy and volume energy density) has been improved. The maximum increase of specific impulse, specific shock energy, specific total energy and volume energy density of emulsion explosive containing titanium hydride is 7.06 %, 8.95 %, 3.97 % and 8.22 %, respectively. Based on the analysis, it is evident that though powdered TiH₂ participates in the detonation reaction process of the emulsion explosive, the majority of TiH₂′s energy is released during the secondary reaction occurring after the detonation wave front. Therefore, the detonation performance of emulsion explosives can be effectively improved by adding a certain mass ratio of titanium hydride.     

含废弃丁羟推进剂的凝胶炸药

为安全处理和再利用废弃固体推进剂,通过添加单基药将丁羟推进剂再利用制备了灌注式凝胶炸药.采用验证板试验及电离探针法研究了不同装药配比、推进剂颗粒尺寸及装药直径对炸药爆轰性能的影响.结果表明,丁羟推进剂难以发生爆轰,若添加适量单基药,能显著提高炸药的爆轰感度,并降低其临界直径;该凝胶炸药密度为1.6 g/cm3,直径为7...     

Critical detonation diameter of industrial explosive charges: Effect of the casing

The critical detonation diameter of industrial explosive charges is analyzed as a function of their state characteristics (composition, density, and structure) and the presence of a casing. The main reason for the increase in the critical diameter with increasing density of ammonium nitrate explosive charges is the reduction in the energy release rate in the chemical reaction zone of the detonation wave. The effect of the particle size of the components and the amount of the sensitizing component on the critical diameter of powdered and granular explosives fits into the concept of explosive combustion. An analytical formula for the critical detonation diameter of emulsion explosives is obtained which correctly describes experimental data. A possible mechanism of the effect of metal casings on the critical detonation diameter is considered for porous explosives whose detonation velocity is lower than the sound velocity in the casing.     

Detonation velocity of BTNEN/Al

The effect of the addition of Al on the detonation velocity of bis(2,2,2-trinitroethyl) nitramine (BTNEN) was studied experimentally. It is shown that the dependence of the detonation velocity of BTNEN on the initial density is nearly linear, and a 75/25 BTNEN/Al mixture is characterized by an increase in the slope of the dependence with increasing density. The addition of Al decreases the detonation velocity of BTNEN. The density range characterized by a maximum decrease in the detonation velocity is determined. A comparison of experimental detonation velocities of BTNEN/Al mixtures with literature data obtained by calculations taking into account a possible change in the phase state of Al₂O₃ showed that the thermodynamic model used in the calculations needs to be improved. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 4, pp. 125–130, July–August, 2006.     

Dependence of detonation velocity on charge density for foamed alumotol (Al/TNT) and TNT mixtures

Experimental data are presented on the dependence of the critical diameter and detonation velocity of cast and liquid porous TNT and TA-15 alumotol (Al/TNT) on charge density. The results of the detonation velocity measurements are compared with calculations. Based on this comparison, it is proposed that the reaction during detonation of alumotol is substantially heterogeneous and this is confirmed by plotting the detonation velocity as a function of density for model mixtures of TNT with various amounts of aluminum and an inert component. Translated fromFizika Goreniya i Vzryva, Vol. 34, No. 4, pp 88–93, July–August 1998.     

Performance of Emulsion Explosives

Some performance of a number of emulsion explosives containing glass micro-baloons were studied experimentally and theoretically. For each of the explosives, detonation velocity was measured and calculated and ballistic mortar tests and cylinder expansion tests were carried out. The results obtained enables a comparison of the usefulness of both testing methods. The influence of some metal nitrates contained in the emulsion matrix on the performance and detonation parameters of the explosives was examined. Key words: explosives, glass micro-balloons, nitrates of metals, detonation parameters, performance.     

Cast aluminized explosives (review)

This paper reviews the current status and future trends of aluminized explosives. The major focus is on cast compositions, which encompass both the melt-cast trinitrotoluene (TNT) based and the slurry cast polymer-based compositions. Widely reported RDX and HMX based aluminized compositions with TNT used as a binder are discussed in detail. Various researchers have suggested a 15–20% Al content as an optimum from the viewpoint of velocity of detonation. A higher Al content, however, is incorporated in most of the compositions for a sustained blast effect, due to the potential of secondary reactions of Al with detonation products. The effect of the aluminum particle size on performance parameters (velocity of detonation, etc.) is included. There are some recent works on nanometric Al based compositions, and the results obtained by various researchers suggest mixed trends for RDX-TNT compositions. Studies on nitrotriazol and TNT based compositions bring out their low vulnerability. Some of the interesting findings on ammonium dinitramide and bis(2,2,2-trinitro-ethyl)nitramine (BTNEN) based compositions are also included. The review brings out superiority of polymer based aluminized explosives, as compared to conventional TNT based compositions, particularly, with respect to low vulnerability. In general, aluminized plastic bonded explosives find numerous underwater applications. Ammonium perchlorate (AP) is also incorporated, particularly, for enhancing underwater shock wave and bubble energy. Hydroxyl terminated polybutadiene appears to be the binder of choice. However, nitrocellulose, polyethylene glycol, and polycaprolactone polymer based compositions with energetic plasticizers, like bis-dinitropropyl acetal/formal (BDNPA/F, 1/1 mix), trimethylol ethane trinitrate, and triethylene glycol dinitrate are also investigated. Polyethylene glycol and polycaprolactone polymer based compositions are found to be low vulnerable, particularly, in terms of shock sensitivity. Highly insensitive polymer bonded nitrotriazol based compositions are being pursued all over the globe. The highly insensitive CL-20/AP combination meets the demands of high density and high velocity of detonation. Glycidyl azide polymer and poly nitratomethyl methyl oxetane appear to be binders of interest for plastic bonded explosives in view of their superior energetics. The vulnerability aspects of these compositions, however, need to be studied in detail. Brief information on plastic bonded and gelled thermobaric explosives is also included. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 4, pp. 98–115, July–August, 2008.     

Heat of explosion of commercial and brisant high explosives

Methods for determining the heat of explosion of high explosives (HEs) with ideal and nonideal processes of explosive decomposition are considered. It is shown that the heat of explosion is of significance for estimating the efficiency of commercial HEs and is used in the energetic characterization of the working capacity. The heat of explosion of brisant HEs is only part of the blast heat of explosion and is the heat content of gaseous detonation products during their isentropic expansion from the initial state to a certain expansion ratio (determined by experimental conditions). The heat of explosion can be obtained by thermodynamic calculations based on physically justified equations of state for fluids (gaseous detonation products in the chemical-reaction zone of the detonation wave in the supercritical state) and condensed nanocarbon phases (nanographite, nanodiamond, and liquid carbon). Experimental and calculated values of the heat of explosion are given. The thermodynamic calculation is inapplicable to commercial HEs because of the nonideal nature of their detonation. The heat of explosion of commercial HEs can be calculated using the Hess law. The heat of explosion of brisant HEs is not a measure of power. The power of HEs is characterized by the propellant performance. It is shown that even detonation velocity cannot be a measure of the power of HEs. The power and detonation parameters of brisant HEs are determined by the energy release density in unit volume of the chemical-reaction zone of the detonation wave and by the rate of energy release from the shock front rather than by the heat of explosion, which cannot be considered a universal characteristic. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 2, pp. 100–107, March–April, 2007.     

Detonation velocity of mechanically activated mixtures of ammonium perchlorate and aluminum

The detonation properties of mechanically activated mixtures of ammonium perchlorate and aluminum were studied. The deflagration-to-detonation transition for low-density charges was investigated. Dependences of the detonation velocity of pressed charges with different types of aluminum on the activation time, density, and diameter of the charges were obtained. For compositions with nanosized aluminum, it is was found that the detonation velocity depends nonmonotonically on the inverse charge diameter and remains almost unchanged in a certain range of charge diameters. It is shown that the joint use of mechanical activation and nanosized components of the composite explosive significantly increases the detonability, reduces the critical diameter, and shifts the maximum of the detonation velocity as a function of density to higher charge densities.     

Performance Properties of Commercial Explosives

The aquarium test is a proven means of obtaining nonidial performance property data for commercial blasting agents. Optical data on the detonation velocity, shock wave in water, and expansion rate of the pipe enclosing the detonation products (in combination with the equilibrium thermodynamic chemistry code BKW) give the C-J state and degree of chemical reaction at the detonation front, as well as information on additional chemical reaction that occurs as the detonation products expand. Specific explosive systems that are studied are ammonium nitrate-fuel oil mixture (ANFO), aluminized ANFO, flaked trinitrotoluene (TNT), and several other commercial products in 10-cm-diam and 20-cm-diam pipes of Plexiglas and clay. Experimental shock pressure data are obtained with lithium niobate transducers placed in the water surrounding the explosive charge. These data show that the addition of ∼ 100-μm aluminum particles to ANFO significantly increases the initial peak shock pressure delivered to the surrounding medium. Peak shock pressures in the water, calculated from the shock-wave orientation, are also useful in comparing performance properties of various commercial explosives.     

叠氮硝胺对发射药枪口焰的影响

为研究1,5-二叠氮基-3-硝基氮杂戊烷(DIANP)对发射药枪口焰的影响,以14.5mm弹道枪为实验平台,采用高速摄影仪测试了不同DIANP含量的发射药枪口火焰参数;分析了DIANP含量及装药质量对枪口焰面积(A)、最大直径(C)、平均直径(D_(mean))和积分光密度(IOD)的影响;分析了叠氮硝胺发射药枪口焰初始火焰、中间焰和二次焰的结构及持续过程。结果表明,在双基发射药中加入DIANP以后,火药力从1 170kJ/kg增至1 189kJ/kg,然后开始降低,发射药爆温基本呈线性降低;发射药爆温及燃烧气体产物组成共同影响枪口焰的形成,DIANP的加入增加了燃烧产物中可燃气体含量,但可以有效降低发射药的爆温;与无DIANP的双基发射药相比,添加DIANP可以降低发射药的枪口焰面积、最大直径、平均直径和积分光密度,当添加DIANP的质量分数为12.5%时,叠氮硝胺发射药样品无二次焰的产生,火焰持续时间为8ms,比传统双基药降低71%。     

Highly Thermal Stable TATB‐based Aluminized Explosives Realizing Optimized Balance between Thermal Stability and Detonation Performance

In this work, a series of TATB‐based aluminized explosives were formulated from 1, 3, 5‐triamino‐2, 4, 6‐trinitrobenzene (TATB), aluminum powders and polymeric binders. The thermal stability, heat of detonation, detonation velocity and pressure of the TATB based aluminized (TATB/Al) explosives were systematically investigated by cook‐off, constant temperature calorimeter, electrometric method and manganin piezo resistance gauge, respectively. The selected PBX‐3 (70 wt% TATB/25 wt% Al/5 wt% fluorine resin) achieved optimized balance between thermal stability and detonation performance, with the thermal runaway temperature around 583 K. The thermal ignition of TATB‐based aluminized explosive occurred at the edge of the cylinder according to the experimental and numerical simulations. Moreover, the critical thermal runaway temperature for PBX‐3 was calculated based on the Semenov's thermal explosion theory and the thermal decomposition kinetic parameters of the explosive, which was consistent with the experimental value.     

Low and High Order Detonation in Tetryl

The detonation behaviour of tetryl has been investigated by analysing published charge diameter effect data for two mesh sizes of powders, using slightly divergent flow theory. Evidence found within the published data for the existence of high and low order detonation velocities regimes has been substantiated. The form of the global heat release function during low order detonation was found to be of the hot spot/grain burning type, and during high order detonation, of the thermal explosion type. Particle size effects are discussed both for low and high order detonation. The observed stability of low order detonation at the smaller charge diameters is explained in the model used, which predicts a ‘forbidden zone’ in shock velocity/inverse charge diameter space. The kinetics are discussed in terms of the pressure dependent functional form used in the CPeX detonation model, and models of hot spot formation in powder explosives.