Strength of Commercial Explosives

Strength is determined for mixtures of Amatol (79/21 AN/TNT) with various additives and mixtures of ammonium nitrate and aluminum of various compositions. The results obtained and literature data are used to obtain a formula for calculating the relative strength of commercial explosives containing two parameters — explosion heat and volume of explosion products. The strength of mixtures of ammonium nitrate and aluminum (under powerful initiation leading to overcompressed detonation) exceeds the strength of the reference explosive (Amatol) when the aluminum content is 10—40%. In this case, maximum strength is observed for a mixture containing 30% aluminum. The experimental results and calculations using the proposed formula are in satisfactory agreement.     

Measurement and calculation of the ideal detonation velocity for liquid nitrocompounds

Results of experimental measurements are presented for the dependence of the detonation velocity on the charge diameter for homogeneous nitromethane and propylene glycol dinitrate and for the ideal detonation velocities for allyl nitrate, diethlyene glycol dinitrate, methylene glycol dinitrate, and ethyl nitrate. Literature data on measurement of the dependence of the detonation velocity on the charge diameter for liquid TNT, nitroglycerin, glycol dinitrate, and methyl nitrate are collected. It is shown that measured values of the ideal detonation velocity are in good agreement with calculated values obtained by the SD method, which uses the equation of state of materials at a high pressure (see B. N. Kondrikov and A. I. Sumin, Fiz. Goreniya Vzryva, No. 1, 1987). A correlation between the ratio of the critical detonation velocity to the ideal velocity and the heat of explosion is obtained, which makes it possible to estimate the limiting value of the latter at which homogeneous liquid nitrocompounds lose detonatability. Translated fromFizika Goreniya i Vzryva, Vol. 34, No. 5, pp. 111–117, September–October 1998.     

Energy release of mixed explosives during propagation of a nonideal detonation under conditions similar to the operation conditions of a blasthole charge

Detonation experiments were performed in a specially developed explosive device simulating a blasthole using charges of fine-grained and coarse-grained (granular) 30/70 TNT/ammonium nitrate mixtures of identical density 0.89 g/cm³ in steel shells with an inner diameter of 28 mm and a wall thickness of 3 mm at detonation velocities of 4.13 and 2.13 km/sec, respectively. Despite significant differences in detonation velocity (pressure), identical expansion of the charge shells was observed. On the other hand, numerical simulations of detonation propagation in the explosive device with the corresponding velocities ignoring the possibility of energy release behind the shock front show that the expansion of the charge shell is always greater in the case of a high-velocity regime. It is concluded that under the conditions simulating detonation propagation and the work of explosion products in a blasthole, effective additional energy release occurs behind the low-velocity (nonideal) detonation front. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 4, pp. 111–120, July–August, 2007.     

Detonation of propane-air mixtures under injection of hot detonation products

The tube for spontaneous detonation (Institute of Technical Physics, Russian Federal Nuclear Center, Snezhinsk) was used to study the initiation and development of detonation in propane-air mixtures under injection of hot detonation products into them. The full picture of this phenomenon was recorded: the injection of hot detonation products into the main tube of the facility with the formation of a mixture of the starting propane-air composition with the hot products; the initiation of a local explosion in this mixture and the subsequent development of a detonation in it; detonation transfer to the region of the cold starting reactants (or detonation failure at the interface). The detonation was found to exist for an initial volume concentration of propane of 3.3 to 5%. The following critical (by the moment of the local explosion) parameters were determined: a mass fraction of hot detonation products of 6–9%, an energy input density due to product injection of 145–195 J/g, and an input energy power of 70–50 J/(g · msec). __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 3, pp. 100–109, May–June, 2006.     

Criteria for estimation of explosion hazard in producing and processing explosives under vibration

The methods and criteria of estimating explosion hazard in processing high explosives (HE) with the use of mechanical effects are analyzed. It is shown that there are no methods and criteria in processing HE using vibrational technology. A new method and a new criterion of estimating explosion hazard upon vibrational processing of HE are proposed. The criterion is calculated on the basis of experimental results concerning the sensitivity of HE to vibration and a comparison of the critical parameters of vibratory loads that cause explosion or significant decomposition of HE with the vibration parameters in processing HE on vibration devices. Examples of the calculation of the safety factor for RDX, TNT, and ammonite upon vibrational pressing and vibrational transportation are given. Translated fromFizika Goreniya i Vzryva, Vol. 36, No. 5, pp. 90–96, September–October, 2000.     

Detonation of ammonium nitrate and dynammons with and without inert additives

The detonation velocities of 10–60 mm thick, flat charges of ammonium nitrate and mixtures of it with various liquid and solid fuels plus added inert components in varied amounts and dispersions are determined experimentally. These explosives have been used for cladding of flat metal stock with areas of up to 12 mm ² by explosion welding with thicknesses of the cladding layer ranging from 1 to 30 mm and of the base layer, from 4 to 120 mm. Translated fromFizika Goreniya i Vzryva, Vol. 35, No. 3, pp. 114–119, May–June 1999.     

Using the tracer method to study detonation processes

The tracer method was used to study the synthesis of nanodiamonds during detonation of composite explosives. Alloys of TNT with RDX, HMX, PETN, and benzotrifuroxan were studied. It was shown that, in all cases, most nanodiamonds were formed from TNT carbon. It was concluded that during the chemical reaction in the detonation wave propagating in heterogeneous explosives, equilibrium parameters were not established. In homogeneous TNT/PETN mixtures, individual components react with each other to form common products. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 6, pp. 92–98, November–December, 2008.     

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.     

Initiation of detonation in hydrogen—Air mixture by explosion of a spherical TNT charge

Direct initiation of detonation by explosion of a TNT charge in a hydrogen—air mixture is considered. The critical mass of initiating charge is determined numerically using a finite-difference method based on the Godunov scheme, taking into account the real chemical kinetics of combustion of hydrogen in air and the real equation of state for gaseous detonation products of TNT. The applicability of the equation of state of a perfect gas to the detonation products of TNT is considered. The effective value of the exponent of Poisson's adiabat is determined.Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 31, No. 2, pp. 91–95, March–April, 1995.     

The Use of Utilizable Explosives to Increase the Efficiency of an Explosion

The possibility of using the utilizable explosives to increase the efficiency of an explosion of industrial high–explosive (HE) charges is studied under laboratory and working conditions. To do this, the explosive charges were used as linear initiators of the elongated charges of industrial HE. It is shown that the placing of an NB–40 ballistite powder rod of diameter 10 mm in a bulk–density TNT charge of diameter 40 mm increases the velocity of acceleration of an aluminum shell by 14% (the ratio between the detonation velocities of the powder and TNT is 1.8 : 1.0). The use of ShZ–1 TNT–based and ShZ–2 RDX–based hose charges in well charges of industrial HE, such as 79/21 Grammonit (79% granular ammonium nitrate/21% scale–shaped TNT), 30/70 Grammonit (30% granular ammonium nitrate/70% granular TNT), and ammonium nitrate, as linear initiators leads to a decrease in the output of bulky rock by 15—20% and allows one to increase the grid of the wells of diameters 160 and 220 mm by 20—25% with preservation of the rock output. The ratio of the detonation velocities of ShZ–1 and ShZ–2 and industrial HE charges is within 1.5—1.7 in the case of 79/21 Grammonit and 2.2—2.6 in the case of ammonium nitrate. The results obtained are explained by the fact that the detonation of a linear initiator from utilizable materials changes the form of the detonation wave front of the basic charge; as a result, it arrives at the surface of an ambient medium at a large angle and a more intense shock wave enters the medium compared to the case without a linear initiator.     

A study of the interaction between the components of heterogeneous explosives by the electrical-conductivity method

The detonation of TNT/RDX alloys is studied by the electrical-conductivity method. The measurement technique is developed with correction for the deformation of electrodes in the explosion. The maximum electrical conductivity of pure TNT was ≈25 Ω⁻¹·cm⁻¹. The addition of RDX decreases the electrical conductivity and width of the conducting zone, which, is, apparently, connected with the formation of diamond. It is shown that the RDX particle size plays an important role. With equal mass fraction, the conductivity of the sample is several times smaller for micron particles than for millimeter particles. This fact is explained by the different degree of mixing of the detonation products of the heterogeneous-explosive components. Translated fromFizika Goreniya i Vzryva, Vol. 36, No. 5, pp. 97–108, September–October, 2000. This work was supported by the Russian Foundation for Fundamental Research (Grant Nos. 99-03-32336 and 96-15-96264).     

铝粉含量对梯铝炸药爆压和冲击波参数的影响

测试了以TNT为基不同含量含铝炸药的爆压和空中爆炸冲击波参数,通过分析铝粉对炸药爆压、空中爆炸参数和爆炸冲击波超压的影响,建立了爆压与铝氧比的关系曲线、5种TNT基含铝炸药的冲击波相似律方程和TNT/Al炸药的爆压与空中爆炸冲击波超压的关系式.结果表明,随着铝粉含量的增加,炸药的爆压呈指数衰减,近距离的冲击波超压也快速减小,但爆炸场温度和爆炸火球的直径及持续时间会增大.     

Destructive effect of accidental explosions of some mixed compositions

This paper deals with issues related to the dependence of the parameters of an air blast wave on the mass of the explosive charge and explosion conditions. It is established that the explosive yield of mixed explosives changes appreciably with variation in the mass of the charge up to the limiting values. After the attainment of the limiting values of the mass, the TNT equivalent ceases to change. The range of charge masses in which the indicated changes are observed depends on the properties of the explosives and is the smaller the less pronounced the stepwise nature of their detonation. The conclusions drawn agree with experimental data. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 2, pp. 105–111, March–April, 2006.     

Formation of a specific layer on the surface of a metallic target interacting with a shaped-charge jet of boron-containing liners

Coatings on titanium targets are obtained under conditions of a shaped-charge explosion; the maximum microhardness of the coatings at certain segments of the target can reach 4000 kg/mm². A conical liner with a cone angle of 20° prepared from a mixture of fine powders of amorphous boron and ammonium nitrate is used in the experiments. A comparative quantitative X-ray powder diffraction analysis of various segments of the coating is performed. The values of the unit cell parameters indicate the formation of complex phases. The dynamics of the results of the X-ray study with the cone angle of the liner decreasing from 45 to 20° is demonstrated. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 2, pp. 121–127, March–April, 2006.     

Density distribution at the detonation front of cylindrical charges of small diameter

A synchrotron radiation based technique is use to study the density distribution at the detonation front and its neighborhood for condensed explosives. Particular data are obtained on the structure of the detonation front in TNT, RDX, and an alloy of TNT with RDX; a comparison of the data with those obtained using different techniques confirms the correctness of the technique. It is concluded that adequate information on the structure of the chemical-reaction zone can be obtained for charges of small diameter. At the same time, it is shown that the Chapman-Jouguet parameters for such charges are far from their predicted values for an infinite medium. The results of the work, including those on the curvature of the detonation front in charges of small diameter, supplement the existing knowledge of the detonation transformation in condensed explosives. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 2, pp. 91–99, March–April, 2007.     

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.     

岩石膨化硝铵炸药的爆破威力研究

研究了岩石膨化硝铵的爆炸性能和爆破威力，在分析岩石爆破机理的基础上，通过与铵梯炸药，铵梯油炸药的爆破性能比较，并根据其自身的爆速高，重量威力大而体积威力稍小的特点，提出进一步提高该炸药爆破威力的技术途径。     

Explosive characteristics of aluminized HMX-based nanocomposites

The explosive characteristics of HMX compositions doped with 15% Al (by weight) were studied experimentally. The detonation velocity, pressure and temperature profiles, the velocity of endwise acceleration of plates, and the heat of explosion of dense pressed samples were measured. The results were compared for compositions based on mechanical mixtures of initial micron-size particles of HMX with aluminum powders of various sizes and for nanocomposites. The addition of nanoaluminum reduces the detonation velocity to a greater degree than the addition of micron-size aluminum. The mechanical mixtures have close detonation velocities, whereas in composites containing different types of nanoaluminum, they differ by almost 200 m/sec. For all compositions, except for the most homogeneous nanocomposite, two-peak pressure profiles are observed. For charges of a composite and a mechanical mixture with nanoaluminum of the same type, the second peak pressures almost coincide but are reached in different times. At the same time, the peak pressure increases with decreasing aluminum particle size. The temperature profiles agree qualitatively with the pressure profiles. The velocity of endwise acceleration of plates depends linearly on the activity of the aluminum powder used. Nanocomposites and mechanical mixtures containing the same aluminum powder have close heats of explosion. Nanoaluminum is almost completely oxidized during calorimeter bomb tests, and the major factor determining the heat of explosion of the compositions with nanoaluminum is also the content of active metal in the aluminum powder. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 2, pp. 85–100, March–April, 2008.     

Influence of HMX particle size on the synthesis of nanodiamonds in detonation waves

The effect of the particle size of HMX in alloys with TNT on the synthesis of nanodiamonds in a detonation wave was studied experimentally. Mixtures with a TNT content of 40 to 90% and the specific surface area of HMX varied in the range of 5–510 m²/kg were investigated. For all mixtures, an increase in the particle size of HMX was found to lead to an increase in the yield of nanodiamonds with the maximum yield shift toward alloys with increased TNT content. The results are explained using a model based on the absence of thermodynamic equilibrium between the components of the heterogeneous explosive during detonation. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 2, pp. 79–84, March–April, 2008.