Detonation characteristics of explosives

Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 28, No. 3, pp. 69–72, May–June, 1992.     

Detonation characteristics of emulsion explosives

The detonation properties of a water-emulsion explosive are studied. The shock adiabat is determined for a density of 1.38 g/cm³. The critical diameter and the detonation velocity are found as functions of the initial density of the charge and the shock heating temperature is calculated.D. I. Mendeleev Moscow Institute of Chemical Technology, Moscow, 125190. Translated from Fizika Goreniya i Vzyrva, Vol.30, No. 3, pp. 86–91, May–June, 1994.     

Detonation characteristics of powerful insensitive explosives

Experimental and calculated detonation characteristics of powerful insensitive explosives are given. Features of explosives with a high hydrogen content are discussed. The relationship between the power and sensitivity characteristics of explosives and the structure of their molecules are considered. Prospects for the development of powerful explosives are discussed.     

Detonation front structure in condensed high explosives

Dzerzhinsk. Translated from Fizika Goreniya i Vzryva, Vol. 24, No. 1, pp. 95–99, January–February, 1988.     

Detonation regimes and Jouguet parameters of condensed explosives

Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 25, No. 2, pp. 84–103, March–April, 1989.     

Mach-Reflection of Detonation Waves in condensed high explosives

In a cylindrical arrangement as deviced by G. R. Fowles and W. M. Isbell for the generation of Mach-reflection of shock waves in solids Mach-reflection of detonation waves in condensed high explosives with different detonation velocities is investigated. The process is observed directly by flash x-ray radiography. By means of this arrangement it is possible to generate via Mach-reflection a plane detonation wave, the Mach-disk. Characteristics and applications of the Mach-disk are discussed.     

Detonation chemistry: Diffusion control in non-ideal explosives

The performance of an explosive is a function of both the peak energy released near the detonation front, and the remainder of the energy that is released during the Taylor wave. The relative partitioning of energy between the front and the expansion, and the rate of energy release in the latter, may be controlled by either chemical kinetic or diffusion processes. Detonation calorimetry has been the principal experimental technique used to investigate these processes. Both the total energy release, and the quantitative analysis of the detonation products at a point or region on the expansion isentrope have been determined for formulations of ammonium nitrate (AN) and TNT in which both the composition and particle size of the AN have been varied. Isotopic labeling of selected explosives has also been used to give further insight into the reactions taking place in or near the reaction zone. Similar experiments have been performed in an ideal, homogeneous explosive.     

Detonation characteristics of diluted liquid explosives: Mixtures of nitromethane with methanol

Detonation in mixtures of nitromethane with methanol as an inert (nonexplosive) diluent is studied. Ignition experiments with mixtures in steel tubes of various diameters provided information on the effect of the degree of dilution on detonability. Mass velocity profiles with a chemical spike characteristic of detonation waves were recorded at the unsteady detonation front in all mixtures studied. This made it possible to distinguish the Chapman-Jouguet state and obtain a fairly complete set of detonation parameters. The dependence of the pressure in the detonation products on the methanol concentration is determined, which is required, in particular, to find the true (absolute) limit of detonation propagation for the concentration of diluted liquid explosives using the method proposed and validated by A. N. Dremin. Some results were found to be inconsistent with one-dimensional detonation theory.     

Detonation characteristics of emulsion explosives sensitized by MgH2

Preliminarily results on the reaction mechanism of detonation of composite emulsion explosives sensitized by MgH₂, which simultaneously plays the role of an energetic material, are presented. Compared to emulsion explosives sensitized by glass microspheres, emulsion explosives sensitized by magnesium hydride have a different reaction mechanism of detonation. The shock wave overpressure, specific impulse, shock wave energy, and bubble energy are all greatly increased with the use of MgH₂, and it is noticeable that the shock wave overpressure and shock wave energy increase by 17% and 24%, respectively. In addition, emulsion explosives sensitized by MgH₂ improve significantly in terms of detonation velocity and brisance. These emulsion explosives also meet safety requirements.     

Detonation characteristics of diluted liquid explosives: Mixtures of tetranitromethane with methanol

Studies of the nature and mechanism of the concentration limit of detonation propagation in dilution of liquid explosives by non-explosive liquids are continued. The impact of dilution of tetranitromethane by methanol on the process of detonation was studied in a wide range of diluent concentrations. Experiments on the ignition of mixtures in steel tubes of various diameter were perfomed to obtain Data on the critical (limiting) diameters. The results obtained were compared with those from previous studies of mixtures of nitromethane with methanol and nitrobenzene. Differences caused by the chemical interaction of tetranitromethane as an active oxidizer with methanol as a fuel component are considered.     

Detonation properties of diluted liquid explosives: A mixture of nitromethane with nitrobenzene

A set of data characterizing the detonation process in mixtures of nitromethane with nitrobenzene is determined with the use of an electromagnetic method. The dependence of the pressure of detonation products on nitrobenzene concentration is established. Information on the effect of dilution ratio of nitromethane by nitrobenzene on detonability was obtained in experiments on mixture explosion. The results are compared with the results of previous similar studies of mixtures of nitromethane and methanol.     

Nanoscale crystal imperfection-induced characterization changes of manganite nanolayers with various crystallographic textures

(La,Sr)MnO₃ (LSMO) nanolayers with various crystallographic textures were grown on the sapphire substrate with and without In₂O₃ epitaxial buffering. The LSMO nanolayer with In₂O₃ epitaxial buffering has a (110) preferred orientation. However, the nanolayer without buffering shows a highly (100)-oriented texture. Detailed microstructure analyses show that the LSMO nanolayer with In₂O₃ epitaxial buffering has a high degree of nanoscale disordered regions (such as subgrain boundaries and incoherent heterointerfaces) in the film. These structural inhomogeneities caused a low degree of ferromagnetic ordering in LSMO with In₂O₃ epitaxial buffering, which leads to a lower saturation magnetization value and Curie temperature, and higher coercivity and resistivity.     

Detonation Products as a Function of Initiation Strength,ambient gas and binder systems of explosives charges

The way of initiating an insensitive high explosive can influence the start of a detonation reaction remarkably. In order to study the extent of this influence, different boosters and different booster structures for the initiation of explosive mixtures containing TNT and nitroguanidine (NQ) have been used. The experiments have been conducted in a 1.5 m³ containment from which the detonation products could be taken and analyzed. In those cases where we only used a 10 g RDX booster together with a detonation cap no. 8, we had not a complete detonation reaction by initiating cylindrical charges of TNT/NQ and TNT/AN. This means that unreacted TNT was analyzed in the solid residue, mainly consisting of carbon soot. On the other hand, we had a complete detonation using an additional booster of about 18 g detonation sheet, placed on the front side of the cylindrical explosive, having the same diameter as the explosive charge. Another part of the investigations deals with the determination of the influence of different argon pressures on the composition of the detonation gas and the solid residue. Between vacuum and one bar argon a strong change not only of the gas but also of the soot residue was measured. A stronger influence on the products was found using a confinement with glass tubes. The investigation of Al-containing charges exhibited a very different behavior compared with charges without Al. No more influence of vaccum or of different ambient gas pressure could be observed. By investigation of two composite explosive charges (PBX) containing binder systems of different energies and different oxygen balances, a great influence on the reaction of Al was found. The PBX charges with the better O₂-balance containing the energetic GAP-binder reacted nearly completely with the Al, opposite to the charge containing the polyisobutylene (PIB) binder system.