Explosion Products Research Articles

DETERMINING THE PERFORMANCE OF EXPLOSIVES FOR BLASTING MANAGEMENT

Experimental methods for determining a performance index of explosives are analysed: the methods of a ballistic pendulum, ballistic mortar, a lead block, and according to the volume of soil explosion funnel. It is defined that the determination of a performance index of emulsion explosives (EE) involves a set of significant features connected with a large critical diameter requiring the experiments with large-mass charges and resulting in refusal from the traditional methods of determining a performance index. Analytical methods for calculating an index of relative performance of explosives are analysed. Determination of the performance indices of explosives with the help of analytical methods helps identify considerable differences in the calculation results; in case of emulsion explosives the results are erroneously low at all. It is since analytical methods do not consider the brisant action of emulsion explosives. This paper represents the developed methodology of determining a performance index of explosives according to the degree of detonation velocity. The proposed methodology considers the key energy and detonation characteristics of explosives: heat and volume of the explosion products, density (thickness), and detonation velocity. The use of analytical methodology for calculating a performance index for all explosive types makes it possible to get correct results that are necessary for designing the parameters of drilling and blasting operations.

Design concepts for explosion products locking in chamber

Design concepts for explosion products locking in chamber

VENTING, REMOTE AIR SAMPLING AND MONITORING OF AIR QUALITY IN BLASTED MINING EXCAVATIONS: CURRENT PROBLEMS AND SOLUTIONS

Objective: to analyze working conditions and safety of miners involved in mining excavations by drilling and blasting and to develop modern schemes and technical solutions to improve their standards. Methodology: comprehensive and detailed analytical studies of the current problems connected with occupational health and safety of personnel working specifically in lifting mine excavations of different purposes were carried out, on the basis of which the key tasks for their practical solution were defined. Results: The preliminary analysis and analytical studies have determined that the main and most acute problems requiring an urgent solution are connected with the ventilation of mine workings, and the need to improve the means of sampling and express-control of the quality of air from the bottom-hole zone of mines. According to the state standard “System of product development and launching into manufacture” (“DSTU 3974-2000”) the fundamentally new integral system of schemes and technical solutions (having no analogs) was developed. The system allows for efficiently and reliably solving the extremely complicated issues of ventilation, dust and gas removal, air quality sampling, and control (express analysis) of air composition in drilling and blasting mining excavations of different purposes (ore mining, ventilation, material-entry) to the height of 80-100 m. The developed equipment includes a multipurpose high-pressure ejector-type automatic dust collector ADC-1, designed for efficient ventilation of lifting workings and providing normal sanitary and hygienic working conditions for tunnelers while performing their work cycle, and for reliable neutralization of explosion products; the modernized device for remote control of air composition RCAC-20/80 ore-welding ventilation and material-entry from the bottom-hole zone of the lifting excavations. This process can be carried out both with the use of standard special indicator tubes with chemical reagents and with the use of modern electronic gas-measuring apparatuses (“Dräger-2500/5000” made in Germany or their analogs). Scientific novelty: the integration, i.e. bringing into a single system, of developed up-to-date technical solutions for effective ventilation, reliable dust and gas extraction, gas removal, and air quality sampling and control of air composition of the lifting workings by the drilling and blasting method.

A Unique Volcanic Jatibarang Reservoir: Facies Characterization and Fracture Calculation

Jatibarang structure, situated in Jatibarang low, one of the prolific sub-basin in the northwest Java basin, belongs to PT. Pertamina EP working area. One hundred seventy wells have been drilled, from which there were 56 production wells. Forty production wells were sunk on a volcanic reservoir. Since 1970, volcanic Jatibarang has faced disputed facies concepts, porosities heterogeneity, and permeability system. A fractured reservoir model was proposed. It was due to unique high-performance hydrocarbon in the early years, and then steeply depleted in the early next 3 years, and flat over 20 years. A unique petrophysical method was developed with various explosives and effusive facies. This study proposes a new facies determination concept related to unavailable default petrophysical plots usually used in the clastic-carbonate reservoir. The new concept of formation evaluation attempts to distinguish the fractured vitric tuff reservoir and non-reservoir zone, which is both effusive lava and explosive product. Reservoirs differed from common clastic-carbonate, typically high gamma-ray reservoir due to potassium feldspar composition. The fracture existence is reflected by a sonic overrunning density log aligned with a deep resistivity pattern. The width of the fracture apertures was measured, and spacing intensities were calculated. Finally, fracture permeability was estimated comprehensively to describe reservoir performance. Property models built with only sonic and triple combo have been debatable; however, advanced logging of JTB-211 has proven this accuracy method.

DEVELOPMENT OF METHODS FOR SURFACE HARDENING OF HARD ALLOY VK10KS

The results of studies of the VK10KS hard alloy after various surface treatments (using concentrated energy flows) are presented. The TiN + ZrN ion-plasma coating from separate titanium and zirconium cathodes was applied using the Kvant-6 installation. The zirconium alloy cathode was located in a chamber between two titanium alloy cathodes.Metallographically, after applying an ion-plasma coating of TiN + ZrN composition, a poorly etched layer with a thickness of 15 microns consisting of microlayers was revealed. The two phases (TiN and ZrN) found in the diffractograms in the coating confirm the micro-thickness of its structure, which will help to increase the adhesion of the coating itself with a carbide base. The boundary between the micro-layers of the coating will inhibit the growth of the crack. It was found that the introduction of zirconium TiN compound into the coating leads to an increase in nanohardness by 23% (up to 39 GPa). Electric spark treatment was carried out on the UR – 121 installation. It consists of erosion of the hardening electrode during spark discharge. At the same time, the erosion products are transferred to the part. A hard alloy VK6-OHM was used as the electrode. X-ray phase analysis revealed the presence on the surface of the hard alloy VK10KS of a newly formed phase with high hardness (divolfram carbideW2C), which has a hardness greater than that of tungsten monocarbideWC. Nanoindentation of the VK10KS alloy after electric spark treatment showed an increase in surface hardness up to 22 GPa. A hardened surface layer consisting of titanium diboride TiB2, carbides TiC, W2C with a nanohardness of 28 GPa was obtained by electroexplosive alloying (EVL) with titanium and boron on a hard alloy VK10KS. The essence of EVL is the accumulation of energy by a battery of pulse capacitors up to 10 kJ and its subsequent discharge within 100 microseconds through a conductor that experiences explosive destruction. At the same time, the treated surface is heated and saturated with explosion products, followed by self-quenching due to heat removal into the environment and deep into the material.

Influence of military actions on the process of the formation of precipitation

This work concerns the study of the influence of military actions on the development of global ecological processes, in particular, the fall of acid rain from individual single explosions. A mathematical model is proposed, which takes into account the emission of pollutants into the subcloud washout zone and the kinetics of the condensation process. The concentration of combustion products in the atmosphere at the level of three to five diameters of the explosion area (the area of the formed explosion funnel) is found using the theory of a convective jet from a warm source to the environment. At the same time, we determined the speed of warm air that rises above the area of the explosion, the average temperature in the transition section of the convective jet, and the flow rate of polluted air in the upper part of the jet. The paper presents a system of dimensionless non-stationary differential equations for a high unshaded source, which can be used to determine the dispersion of the main acid-forming substances in the Boussinesq approximation with the variables "eddy velocity – current function – temperature – concentration" with appropriate initial and boundary conditions. Sulfuric anhydride was considered as an example of the main acid-forming substances and the most dangerous and toxic compounds of explosion products. The proposed mathematical model can be used to forecast the possible fall of acid rain on the territories adjacent to single explosions, thereby making a forecast of changes in environmental risk as a result of military operations for the environment and the population. and will make it possible to determine the zones of influence and dispersion from the place of the explosion.

Fragment characteristics of cylinder with discontinuous charge

In real applications of warheads, not all charges are continuous. For specific purposes, such as power control and intermittent initiation, non-explosive materials are filled into the casing, which caused the charge to be discontinuous. In addition, detonators and control devices are often used with non-explosive materials. The effect of axial discontinuity of the charge on the fragment was not considered. In this study, we assumed that the non-explosive material was air, and divided the cylinder axially into charge and air parts axially. Existing formulae can neither accurately forecast fragment velocity from the charge part, nor predict that from the air part because of the non-existence of explosives. A cylinder with a discontinuous charge was investigated using a numerical method, and two charge parts were detonated from the air part because the initiator was usually in the non-explosive material to save space. It was found that the explosive products from the two charges were superimposed in the middle of the air part, forming a superimposed high-pressure zone, which accelerated the air part and the charge part casings near the air part. The influence distance of the superimposed high-pressure zone on the charge parts is 2R, where R is the charge radius. A formula was established to predict the fragment velocity distribution. The simulation results were verified by X-ray radiography, where the circumferential half casing of each specimen was semi-preformed and the other half was natural. It was found that the project angle and axial density of the fragments were related to the axial-driven energy gradient but not to the shear stress exceeding the dynamic shear strength. The air part of the semi-preformed shell overlapped and formed a dense zone, whereas that of the natural shell broke at three abrupt axial-driven energy gradients and formed two fragments with greater mass and kinetic energy. The experimental data showed that the average relative error of the proposed formula was less than 4.5%, indicating that the proposed formula can predict the fragment velocity distribution from such a cylinder with sufficient accuracy. This study provides a basis and reference for the study of cylinders with discontinuous charges.

Thermal explosion synthesis of Cr2AlB2 materials

Abstract Ternary conductive ceramic Cr2AlB2 phase has been widely studied because of its unique physical and chemical properties. However, the preparation of conventional synthetic Cr2AlB2 requires expensive raw materials or higher equipment cost, which is not conducive to its synthesis and promotion. Hence, we synthesized high-content Cr2AlB2 by thermal explosion reaction, a technology with low-energy consumption. Cr2AlB2 was synthesized by thermal explosion reaction from Cr/Al/B mixed powders. The effects of different ignition materials and diamond additive on Cr2AlB2 synthesis were studied systematically. Results showed that the Cr/Al/B system did not undergo a thermal explosion reaction. An aluminothermic reaction between Al and Cr2O3 occurred by introducing a small amount of Cr2O3. The main phase of the thermal explosion products of the Cr/Al/B/Cr2O3 green body was CrB. The addition of an appropriate amount (7.5 % and 10 %) of diamond in the raw material can obviously promote Cr2AlB2 synthesis. The main phases of the product were Cr2AlB2 and CrB. The samples were composed of a large number of fine Cr2AlB2 lath grains. Finally, the mechanism of Cr2AlB2 formation by thermal explosion reaction was proposed.

Dust explosion in fusion reactors: Explosion characteristics and reaction mechanism of tungsten micro-powder

The explosion of in-vessel dusts, mainly produced by energetic plasma and wall interaction, will pose a great threat to the safe operation of a fusion reactor. Unlike dust explosions in traditional industrial systems, dust explosion in tokamak devices has the unique characteristics, including dust composition (tungsten is one of the main components), initial conditions of explosion, etc. However, the experimental data on this aspect are very few, which is not enough to support the safety assessment of fusion reactors. In this work, the experiments were used to study the explosion characteristics and mechanism of the micro-tungsten in a 20 L spherical vessel. Results showed that the lower explosion limit (LEL) of 2 µm tungsten dust was in the range of 250–500 g/m3, and the maximum explosion pressure would reach 0.46 MPa at 3000 g/m3. The factors related to fusion reactor environment, including initial pressure, ignition energies and the ignition delay time, were studied to demonstrate a significant effect on explosion parameters. The explosion product changed from WO3 to WO2.72 with the increase of nominal dust concentration. A combustion mechanism for single mirco-tungsten particle was established. Based on the experimental data, the explosion possibility and hazard of tungsten dust in fusion reactor were also dicussed.

Experimental study on the suppression of coal dust explosion by silica aerogel

Silica aerogel (SiA) is prepared using environmentally friendly material diatomaceous earth and its effect on coal dust explosion is studied. The coal dust explosion characteristics experiments are carried out in a 20 L spherical explosion tank and dust explosion flame propagation experimental system, and the coal dust explosion products are analyzed by FTIR and XPS test methods. The results showed that after adding 50% SiA, the maximum explosion pressure of coal samples decreased from 0.3813 MPa to 0.1854 MPa, (dp/dt)max decreased from 10.955 Mpa/s to 4.082 Mpa/s, weakening by 62.74%, and the flame propagation height decreased from 567.57 mm to almost no flame propagation observed; using the Coats- Redfern method to calculate the activation energy of coal and SiA in the slow reaction stage of 30.353 kJ/mol and 21.159 kJ/mol, indicating that SiA preferentially consumes oxygen in the confined space, slowing down the oxidative pyrolysis of coal; SiA attenuates the impact energy generated by the explosion, protects part of the functional groups of coal from being destroyed, and inhibits the decomposition of some C elements in coal; proposes reduce the thermal radiation effect and decompression deceleration coupling effect to describe the inhibition mechanism of SiA on coal dust explosion.

Полуэмпирический анализ начальной стадии роста очага разложения за фронтом ударной волны

The paper presents analysis results of the initial stage of decomposition of phlegmatized RDX behind the front of a shock wave with pressure at the front approximately equal to 2 GPa, presumably during the time preceding the merging of the initially isolated decomposition centers. In this case, the time dependences of the mass fraction of explosive decomposition products behind the shock wave front and their specific volume obtained by processing the results of experiments carried out by the method of quasi-thin layers (layers tenths of millimeters thick placed between blocks of an inert reference material) are used. Based on the dynamics of changes in the parameters of the state of the reacting charge revealed from the results of the experiment, the time dependences of the characteristics of the matrix explosive movement around the decomposition site were established within the framework of an elementary spherical charge cell model. It is taken in the form of a sphere containing a central pore filled initially with air. Time dependences (within tenths of a microsecond) of the radius of the decomposition site, represented as a spherical cavity filled with explosive combustion products and compressible initial pore gas, are obtained; tangential deformation and its velocity on control spherical surfaces located at different distances from the surface of the decomposition site; strains and strain rates on the spherical combustion surface are revealed. The influence on the estimates of these characteristics of the concentration of decomposition sites in the range of variation 1012....1013 m–3 and the residual air pressure in the pores remaining after the pressing of charges (0,1 MPa and 1 MPa). Deformations and strain rates on the surface of the decomposition site, considered as a combustion surface, can reach values equal to 25% and 106 1/s, respectively. The surface area of the decomposition site can be an order of magnitude greater than the combustion surface area, which would be if the specific volume of decomposition products was not significantly less than that of the explosive. The speed of displacement of the surface of the decomposition site can exceed the linear combustion rate by an order of magnitude.

ПРОИСХОЖДЕНИЕ АВТОНОМНЫХ РОССЫПЕЙ АЛМАЗОВ

The obtained evidences of the hot accretion of Earth indicates that kimberlites, lamproites and diamonds were formed from residual melts of the bottom peridotite parts in global magmatic ocean generated as a result of the huge impact heat input during accretion. Rhombic-dodecahedron and rounded diamonds, characteristic of autonomous placers with an unknown mother lode, appeared in relatively silicic acid-rich viscous magmas. The low content of carbon dioxide in them led to a small boiling depth, decompression solidification and explosion of solidified parts of rising pyrogeic columns under the influence of the high internal pressure of gas phase preserved by solidification and to the formation of explosive diatremes insignificant in volume. Therefore, explosion products were ejected mainly onto the Earth’s surface and formed diamond tuffs and tuffizites. Their wash out has led to the formation of autonomous diamond placers, for which it is not possible to find kimberlite pipes, the supposed mother lodes of diamonds.

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.

Theoretical insight into the acidity and cooperativity effect of the LLM-105∙(HNO3)2 system.

In order to reveal the nature of the acidity in explosive product, the acidities and cooperativity effects from the intermolecular H-bonding interactions in the LLM-105∙∙∙(HNO3)2 ternary systems were investigated at the B3LYP/6-311 + + G** and M062X/6-311 + + G** levels, with the integral equation formalism polarized continuum model (IEFPCM) based on the self-consistent-reaction-field. The results show that for the ternary systems, the intermolecular H-bonding interactions are stronger than those in the binary complexes, resulting in the lower [H+] concentrations and larger pKa1 values upon the ternary-complex formations. However, there is no obvious correlation between the acidities and cooperativity effects or APT charges of the H atoms involving the H-bonds. Surface electrostatic potential (ESP) and reduced density gradient are used to reveal the nature of the H-bond and acidity. Interestingly, the acidity is closely related to the ESPs of the H atom (VS,H) involving the intermolecular H-bond, but not to the statistical quantities. This is mainly because both acidity and VS,H are the local properties of system, whereas the cooperativity and statistical quantity of ESP are the global property.

New correlations for evaluating the equivalent bare charge mass for a cased charge

Munitions contain casings that consume explosive energy. The blast load (e.g., peak overpressure and maximum impulse) intensity generated by ammunition explosion will be lower than that generated by a bare charge with equal mass. To evaluate the blast load of a cased charge under different conditions, the equivalent bare mass needs to be calculated. However, the accuracy of existing correlations strongly depends on the empirical determination of relevant controlling parameters and lacks theoretical clarification. In this paper, new correlations are proposed based on a more rigorous theoretical derivation, considering both the mechanical behaviors of the casing’s material and the change of the polytropic exponent during the expansion process of the explosion products. The controlling parameters are attributed to the rupture radius ratio and the polytropic exponent of detonation products expansion to casing rupture state. The reasonability is validated by both comprehensive numerical simulations with dynamic mechanical constitutive model and theoretical derivations. The results calculated by the new correlation show better agreement with the experimental results than those calculated by previous correlations, and the results difference is explained in more consistency with the thermos-physical properties of the charge and mechanical behaviors of casing material. Furthermore, the correlation of the cased-to-bare impulse ratio is also theoretically improved, providing a more accurate theoretical basis for both the equivalent bare mass and impulse evaluation for a cased charge.

Spatiotemporally resolved 5-MHz visualization and particle image velocimetry in early time multiphase blasts

Explosive blasts, used in a variety of engineering applications, have coupled multiphase dynamics, and require high-fidelity spatiotemporally resolved measurements to understand and accurately predict key design parameters. This study evaluates burst-mode laser-based particle-field visualization and particle image velocimetry (PIV) for planar measurements up to 5 MHz. This enhancement of time-resolved PIV represents an order-of-magnitude increase over the prior state of the art enabling measured velocities in the km/s regime. The technique is applied to a multiphase blast’s early (<10 µs) development to quantify the cross-sectional flow structure, velocity, acceleration, and pressure within the rapidly expanding particle field. The morphological evolution of the solid explosive products is characterized by a scale-independent shape parameter and the fractal dimension. This analysis highlights two flow development regimes (separated by 2 µs) in the expansion process. The high measurement resolution enables the characterization of significant differences in velocity and acceleration between the primary and secondary expansion directions. These orthogonal directions are located where the shock is attached and detached respectively from the solid products: each is driven by different forces in the flow. These measurements yield information about complex transport processes and may be useful for subsequent validation of high-fidelity multiphase blast simulations.

Advective nature of ring crater structures on the Moon and Earth, &#x0D; problems of their astrobleme interpretation

In this paper, we compare different-scale ring crater structures on the surface of the Moon and the Earth. Here we show the regular zonal change of craters of different sizes around the largest crater on the Moon and the periodicity of the distribution of craters along the lines according to the wave principle. On Earth, we consider the position of the famous Arizona crater, the relationship with the external environment and structural features that cast doubt on its astrobleme nature. Arguments are given about the possible terrestrial origin of the specific largest iron meteorites found without craters, and the ambiguous diagnosis of explosion products attributed to those associated with meteorite impacts.

Effect of afterburning effect of aluminum powder on shockwave and bubble behavior of CL-20 explosive in deep-water explosion

ABSTRACT Aluminized explosives are widely used in underwater explosives, and their energy release follows a typical time-varying process involving two stages: explosive detonation and afterburning of aluminum powder. Simulated deep-water explosion experiments of hexanitrohexaazaisowurtzitane (CL-20)-based explosives were conducted using a deep-water explosion pressure tank to study the effect of aluminum powder combustion on the shockwave propagation and bubble pulsation of deep-water explosions. The distribution mechanism of aluminum powder afterburning energy in the process of shockwave propagation and bubble pulsation under a high hydrostatic pressure was clarified, and the effect of aluminum contents on the bubble behavior of deep-water explosion was obtained by the proposed calculation method of bubble behavior. The results showed that the pressure of the shockwave of the CL-20-based aluminized explosive was lower, and the energy released by the combustion of aluminum powder increased the pressure in the middle and end of the shockwave’s trailing edge, reduced the shockwave attenuation rate, and increased the first bubble pulse pressure and pulse period. The afterburning phenomenon of aluminum powder in the CL-20 aluminized explosive in explosion bubbles under high hydrostatic pressures was captured in the simulated deep-water explosion experiment for the first time. It was proven that the combustion time of the micro-aluminum powder was at the millisecond level, and the maximum radius of the bubble increased with the afterburning of aluminum powder. The characteristic parameters of the first pulsation of the CL-20-based explosive with different aluminum content in deep-water explosions calculated by the second-order Mach accuracy bubble dynamics equation and the equation of state of the explosion products were within 7% of the experimental values. The change of the afterburning process of the aluminum powder caused by the aluminum content has a great influence on the bubble behavior, and through the design of aluminum content, ideal deep-water explosion bubble characteristic parameters can be obtained.

New Inferences on Magma Dynamics in Melilitite‐Carbonatite Volcanoes: The Case Study of Mt. Vulture (Southern Italy)

AbstractThis study provides the first micro‐thermometric data of fluid inclusions (FIs) in mafic loose (disaggregated) xenocrysts and ultramafic xenoliths in explosive products of the melilitite‐carbonatite Mt. Vulture volcano (southern Italy). Pure CO2 late stage FIs hosted in rock‐forming minerals of wehrlite xenoliths and clinopyroxene xenocrysts were trapped at the local crust‐mantle boundary (32 km). In contrast, trapping pressures within the loose olivine xenocrysts are from 3.2 to 4.5 kbar (8–13 km). Considering the ongoing degassing of mantle‐derived CO2 rich gases, together with seismic evidences of the presence of low amount of melts at depth, and the tectonic control of the past volcanic activity, our study opens new perspective about the hazardous nature of the “quiescent” melilitite‐carbonatite volcanoes.

Compositionally graded multi-principal-element alloy coating with hybrid amorphous-nanocrystalline structure by directional electrical explosion

Electrical explosion, characterized by ultra-fast atomization and quenching (dT/dt ∼1010–1012 K/s) of the sample, is a unique approach for the one-step synthesis of nanoparticles or coatings. A dense μm-thick alloy coating made of AlCuTiMoWSn was manufactured via the pulsed-discharge-driven intertwined wire explosion in μs-timescale. The explosion products were guided by a nozzle, forming a thermal plasma jet spray (km/s) towards the substrate. The condensation and stacking of those elements on Si wafer appeared graded element distribution, on account of the discrepancy in electrical explosion dynamics of various metals and the jet-wall interaction effects. High-speed photography along with electro-physical diagnostics was applied to characterize the dynamics of the synthesizing process. Scanning electron microscopy and energy dispersive spectrometer were used to capture the microstructural and compositional features of the coating from the top/sectional views. The results indicate the discordance in electrical explosion causes various element abundance and phase states at different depths of the coating. Specifically, Sn is the first to explode and spray toward the Si wafer, then Al/Cu, and finally Ti/Mo/W. Morphology and x-ray diffraction results confirm the co-existence of nanocrystalline and amorphous phase for the alloy coating. In addition, the quenching, nucleation, and condensation are deeply associated with fluid dynamics such as turbulent mixing, near-wall vortex, etc. Also, the influence of nozzle configuration was discussed. This ingenious path could favor fabricating materials suited to applications demanding variable mechanical/electrical functions.