Electrical Wire Explosion Research Articles

Laser scattering by submicron droplets formed during the electrical explosion of thin metal wires

This paper presents the results of studying dispersed media formation during the electrical explosion of thin metal wires in vacuum by using low-current generators (∼1–10 kA). Particular attention is paid to the analysis of the composition and structure of the corresponding explosion products as well as to the problem of their visualization using simultaneous laser interferometry and shadow imaging at two wavelengths (1.064 µm and 0.532 µm). Our findings indicate the important role in the visualization of the explosion products that belongs to multiple scattering by submicron droplets of dense condensed matter, which are mixed with metal vapor. The hypothesis on the existence of submicron droplets in the products of exploding metal wires correlates with the results obtained by soft x-ray radiography combined with a laser probing technique. Taking into account the multiple scattering by submicron droplets, it is possible to significantly clarify the parameters of the explosion products visualized via laser probing techniques as well as to gain a deeper insight into the physics behind the electrical wire explosion.

Compact high-current pulse generator for laboratory studies of high energy density matter.

We present the design and parameters of a compact and mobile high-current pulse generator, which can be applied in the study of warm dense matter in university laboratories. The generator dimensions are 550 × 570 × 590mm3, the weight is ∼70kg, and it consists of four "bricks" connected in parallel. Each brick, made up of 2 × 40 nF, 100 kV low-inductance capacitors connected in parallel, has its own multi-gap and multichannel ball gas spark switch, triggered via a capacitively coupled triggering by a positive polarity pulse of ∼80 kV amplitude and ∼15ns rise time. At a charging voltage of ∼70 kV, the generator produces a ∼155 kA current pulse with a rise time of ∼220ns on a ∼15 nH inductive short-circuit load and a ∼90 kA amplitude current pulse in the underwater electrical explosion of a copper wire.

Compacting nanopowder materials by a pulse pressure generated by expanding plasma channel of a spark ignited by wire electrical explosion

The purpose of the article is to explore the possibilities of powder material compaction by the pressure pulse of an electric explosion of a conductor, establish a functional relationship between the parameters of the pressure pulse and an electrical technological installation for powder material compaction, select the parameters for pulse pressure amplitude and duration adjustment, and specify the design options of the working tool for powder material compaction. Analytical studies have been carried out on the basis of the method of formalized representation of the development of the process of pulse pressure wave formation and propagation where the latter is created by an expanding plasma channel of an electric spark in a transmitting medium initiated by an electric explosion of a wire. The simulation of high-speed de formation of the pipe wall under the action of the pulse pressure is carried out in the MATLAB software package. A scanning electron microscope is used to study the microstructure of the breakage of the compacted material with nanomodifiers. Based on the experimental studies on powder material compaction by the pulse pressure created by the expanding plasma channel of a spark initiated by an electric explosion of a wire when the current pulse f rom an electrotechnological installation is supplied to it, it has been determined that the magnitude and shape of the pressure pulse are most influenced by the parameters of this installation. Based on the obtained model studies, the optimal modes for compaction of nanomodified powders have been selected. The relationship is obtained between the parameters of the pulse pressure (Pm amplitude and pressure wave propagation form) and the electrotechnological installation (voltage, inductance, capacitance). It is proposed to use an acoustic-electric wave model to estimate the pressure that provides high-speed deformation of metal pipes, and to plot a deformation profile of metal pipes used for compaction. Analysis of SEM images of the fractures obtained in compact experiments has showed a high degree of particle compaction with the formation of a solid composite.

Formation of Structural-Phase States in Ag–Cu Bimetallic Nanoparticles Produced By Electrical Explosion of Wires

Formation of Structural-Phase States in Ag–Cu Bimetallic Nanoparticles Produced By Electrical Explosion of Wires

Особенности формирования титаната цинка при электровзрывном диспергировании титанового и цинкового проводников в кислородсодержащей атмосфере

In present work, we have synthesized, for the first time, zinc titanate nanoparticles by electric explosion of titanium and zinc wires in an oxygen-containing atmosphere (argon - oxygen 20 vol. %). As-synthesized nanoparticles nanoparticles were characterized using transmission electron microscopy, X-ray analysis, and X-ray photoelectron spectroscopy. The particles have a spherical shape and an average particle size of 82 nm. The phase composition is presented by zinc titanate and a small amount of titanium oxide, which corresponds to the phase diagram of the TiO2-ZnO system. The photocatalytic activity of the synthesized nanoparticles was studied in the decomposition reaction of a model dye methylene blue and it was found that it was higher than that of titanium oxide nanoparticles obtained by electric explosion of a titanium wire in an oxygen-containing atmosphere. In addition, the synthesized nanoparticles demonstrated high antibacterial activity against MRSA bacteria.

Cu–Fe nanoparticles containing nanocomposites: synthesis, stabilization and antibacterial activity

Currently, soft hydrogels with antimicrobial properties are widely used in biomedical applications as dressings and wound healing agents. In the present work, Cu–Fe nanoparticles with different component ratios were obtained by the joint electric explosion of iron and copper wires in an argon atmosphere. Bimetallic nanoparticles had a clear interface between the iron and copper phases at the particle level. Cu–Fe nanoparticles had high antibacterial activity against a wide bacterial spectrum. In connection with dusting and entrainment of nanoparticles, for the convenience of biomedical application, compositions were created based on non-toxic biocompatible polymers – polyvinyl alcohol, polyacrylic acid, and polyacrylamide. The suspension of nanoparticles was pretreated with ultrasound for 5 min at a frequency of 22.4 kHz. Polyvinyl alcohol was used as a nanoparticle stabilizer. The stability of the suspension was investigated by the sedimentation method. The resulting compositions effectively inhibited the growth of Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 6538, methicillin-resistant Staphylococcus aureus ATCC 43300 (MRSA), and Pseudomonas aeruginisa ATCC 9027.

Fabrication and Characterization of Immiscible Fe-Cu Alloys using Electrical Explosion of Wire in Liquid

Iron and copper are practically immiscible in the equilibrium state, even though their atomic radii are similar. As non-equilibrium solid solutions, the metastable Fe-Cu alloys can be synthesized using special methods, such as rapid quenching, vapor deposition, sputtering, ion-beam mixing, and mechanical alloying. The complexity of these methods (multiple steps, low productivity, high cost, and non-eco-friendliness) is a hinderance for their industrial applications. Electrical explosion of wire (EEW) is a well-known and effective method for the synthesis of metallic and alloy nanoparticles, and fabrication using the EEW is a simple and economic process. Therefore, it can be potentially employed to circumvent this problem. In this work, we propose the synthesis of Fe-Cu nanoparticles using EEW in a suitable solution. The powder shape, size distribution, and alloying state are analyzed and discussed according to the conditions of the EEW.

In English

n-TiO2 and n-TiO2:Ag nanopowders were synthesized by the method of electric explosion of wires (EEW). The doping of nanopowders took place during the explosion of titanium wire, on the surface of which an Ag2O layer of the appropriate mass was applied. The energy of the explosion was equal to Е = 3.1·Еs, where Es is the energy of sublimation of the metal. Based on the synthesized nanopowders, mesoporous n-TiO2 and n-TiO2:Ag films were formed. The phase composition of the surface of several series of n-TiO2 and n-TiO2:Ag samples under different annealing conditions was studied by X-ray photoelectron spectroscopy. The XPS spectra of the Ti2p- and Ag3d- levels were decomposed by the Gauss-Newton method into interconnected components 2p3/2/2p1/2 and 3d5/2/3d3/2 with parameters DЕ = 5.76 eV; I1/I2 = 0.5 and DЕ = 6.0 eV; I1/I2 = 0.66 to take into account the spin-orbit splitting of the pair respectively. The paper presents histograms of the contributions of the components to the Ti2p- and Ag3d- spectra, which vary depending on the degree of doping and annealing conditions for 4 series of samples. According to XPS data, on the surface of EEW nanopowders TiO2 and TiO2:Ag titanium is represented by Ti3+- and Ti4+- states, silver by Ag0-, Ag1+- and Ag2+- states. In all series of samples, the contribution of the Ti3+- state simultaneously increases with an increase in the absolute Ag content, which is a consequence of the lattice distortion through the formation of a surface phase with Ti–O–Ag bonds. Annealing at 300 °C in air leads to an increase in the contribution to the spectra of Ti4+- states of ЕbTi2p3/2 = 458.3 eV and Ag1+ - states. Pretreatment of the samples with hydrogen peroxide before annealing leads to an increase in the contribution of oxide-hydroxide phases of titanium and Ag0- states. Annealing of the samples at 300 °С in argon with pretreatment with hydrogen peroxide leads to an increase in the contribution to the spectra of Ti4+- states with ЕbTi2p3/2 = 458.8 eV, oxide-hydroxide phases of titanium and Ag0. It has been found that the direction of redox processes on the surface of n-TiO2 after the action of H2O2 and subsequent annealing in air depends on the state of hydration of the original nanopowders.

Size-dependent phase stability of silver nanoparticles

A comparative analysis of the structure of silver nanoparticles obtained by chemical synthesis (citrate method) and electrical explosion of wires is carried out. The structure, phase composition, lattice parameters of silver nanoparticles with sizes from 2 to 50 nm were studied by electron diffraction and high-resolution transmission electron microscopy. All silver nanoparticles obtained by the chemical method have only a cubic structure. Silver nanoparticles obtained by the physical method have cubic and hexagonal structures. The existence of the hexagonal phase under normal conditions is explained by the quenching effect. The lattice parameters of the cubic phase of Ag NPs within the experimental determination error (± 0.01 nm), synthesized by the chemical method and by the method electrical explosion of wires do not differ from each other.

Thermochemical Analysis of the Interaction between Interfaces in Composites Containing Nanodispersed Powders of Al and Al2O3

Isothermal microcalorimetry is used to study interfacial interaction in composite films based on electron-donor (polystyrene) and electron-acceptor (polyvinyl chloride) polymers containing Al and Al2O3 nanodispersed powders obtained via the electrical explosion of wire. According to the enthalpies of adhesion in composites and the enthalpies of wetting of dispersed powders with solvents of different chemical natures, it is found that Al2O3 surfaces exhibit mainly electron acceptor properties in interfacial interaction, while Al surfaces display both acceptor and donor properties. The results from calorimetric studies are consistent with data from IR spectroscopy of composite films.

Flame propagation behavior of aluminum nanopowder in bulk layer

The flame propagation parameters of aluminum nanopowder in the bulk layer were investigated. The aluminum nanopowder produced by the method of the electrical explosion of wires used in this study. The aluminum bulk layer was ignited by open flame, heated body, or electric spark. The flame propagation behavior is described as a two-stage process: 1) flame propagation over the surface layer and deep into the sample; 2) the thermal explosion mode. It was found that the type of ignition source influences the parameters of the first stage of the combustion. The minimum ignition energy for the aluminum nanopowder bulk layer was measured. The effect of the bulk layer inclination angle on flame propagation parameters was determined. The obtained results can be useful in assessing the fire hazard and organizing safe processes of industrial production during the use, storage, handling, and transportation of metal nanopowders.

Temperature of metal wires for nanosecond and microsecond electrical explosions in vacuum

Experiments show an inverse correlation between temperature and heating time for the electrical explosion of thin metal wires in vacuum. Faster heating of the wire results in higher energy release in a short time, while slow heating lasts longer but releases less energy before breakdown. Breakdown is a natural barrier to the direct release of Joule energy and an increase in the metal temperature to an abnormally high value. An increase in the current rate from 0.07 to 170 A/ns leads to a decrease in the heating time from 5 μs to 5 ns and an increase in the wire temperature from 450 K to 4000 K before the voltage breakdown. This inverse correlation between the heating time and the temperature of the wire in a vacuum can be explained by the inertia of evaporation of the hydrocarbon impurity from the surface of the hot metal.

Stratification and filamentation instabilities in the dense core of exploding wires

We report experiments characterizing the stratified and filamentary structures formed in the dense core of nanosecond electrical explosion of aluminum wires to understand the physical scenario of electrothermal instability. Direct experimental observations for stratification and filamentation instabilities, as well as the coexistence state of azimuthal strata and vertical filament in the dense plasma column, are presented. The wire core exhibits remarkable different patterns of instability with the decreasing wire length. The shadowgram of shorter wires demonstrates that the instability is transformed from stratified structures to filamentary structures. According to a radial magnetohydrodynamic computation, the wire enters a phase state of negative temperature dependence of resistivity before voltage breakdown. However, filamentary structures are only observed in exploding wires of 1 cm and 0.5 cm in length. The analyses based on experimental and computational results indicate that the increase in internal energy determines the manifestation of instability in the dense core. Filamentation instability occurs when the total energy input is no less than 1.5 times the vaporization energy at the moment of voltage breakdown. The lower limit of energy deposition ensures that the increase in internal energy covers vaporization energy.

Ag–Cu/Pmma Nanocomposites Produced By Modification of PMMA with Bimetallic EEW-Nanoparticles

Using the method of electrical explosion of copper and silver wires in an argon atmosphere, Cu–94Ag, Cu–65Ag, and Cu–22Ag bimetallic nanoparticles are manufactured. The resulting nanoparticles are characterized by the methods of transmission electron microscopy and X-ray diffraction analysis. It is shown that irrespective of the component ratio all particles have spherical shapes, with copper and silver uniformly distributed in their volume. The phases identified in the samples correspond to silver- and copper-based solid solutions. The conditions for an ultrasonic dispersion of nanoparticle suspensions are selected. The sedimentation analysis data indicate that the minimal time of ultrasonic treatment at a power of 23 kW is 5min for Cu–65Ag and Cu–22Ag nanoparticles and 2 min for Cu–94Ag nanopowder. The fabricated nanoparticles are used as antibacterial modifiers of PMMA. The Ag–Cu/PMMA composites demonstrate a high antibacterial activity against Escherichia coli.

High-speed imaging of transition from fluid breakup to phase explosion in electric explosion of tungsten wires in air

High-speed visible imaging of sub-microsecond electric explosion of wires at the low specific energy deposition threshold reveals three distinct modes of wire failure as capacitor charge voltage and energy deposition are increased. For 100 μm diameter gold-plated tungsten wires of 2 cm length, deposited energies of 1.9 eV/atom produce a liquid column that undergoes hydrodynamic breakup into droplets with radii of the order of wire diameter on timescales of 200 μs. Instability growth, column breakup, and droplet coalescence follow classical Rayleigh–Plateau predictions for instability of the viscous fluid column. Above a deposited energy of 3.2 eV/atom, wires are seen to abruptly transition to an expanding mixture of micrometer scale liquid-droplets and vapor within one frame (less than 3.33 μs), which has been termed “phase explosion” in the literature. Between these two limits, at a deposited energy of 2.5 eV/atom, the wire radius remains unchanged for the first 10 μs before the onset of a rapid expansion and disintegration that resembles homogenous nucleation of mechanically unstable bubbles. Thermodynamic calculations are presented, which separate cases by temperature obtained during heating: below the boiling point, near the boiling point, and exceeding the boiling point.

Detection of Cells Containing Internalized Multidomain Magnetic Iron (II, III) Oxide Nanoparticles Using the Magnetic Resonance Imaging Method

This study evaluated the feasibility of using uncoated iron (II, III) oxide nanoparticles (IONP) obtained by electric explosion of wire in air for labelling living mesenchymal stromal cells and their subsequent visualization by magnetic resonance imaging (MRI) using the 1T and 1.5T clinical MRI scanners. The uptake of uncoated IONP by MSC was demonstrated for the wide range of IONP concentration in the cell culture medium. The cells did not change their proliferative activity, viability, and the set of surface markers. Iron oxide nanoparticles obtained by an electric explosion of wire in an atmosphere of air had a shape close to spherical. According to dynamic lateral light scattering, laser diffraction, and transmission electron microscopy, the particle size varied from 14 to 136 nm. Particles up to 136 nm accounted for 75%, while particles less than 36 nm accounted for 10%. A wide range of particle sizes made it possible to select MRI parameters suitable for labelled cells detection in animal tissues in both the T2 and the T1 relaxation mode.

Application of Silver Nanofluids on Kinetics of Sulfur Hexafluoride Gas Hydrate Formation.

Gas hydrates are nonstoichiometric nano-structured crystalline compounds which are stabilized by gas molecules incorporated in the cages made of hydrogen bonding of water molecules at suitable thermodynamic conditions. The gas hydrate as a technology has been successful for several potential applications in various engineering fields, such as, gas separation, carbon dioxide sequestration, gas storage and transportation, desalination of salt water and wastewater treatment. Recently, metal-based nanofluids are considered as interesting kinetic promoter candidates for accelerating formation of gas hydrates. Although organic-based kinetic promoters are widely studied for the rapid formation of gas hydrates, research of a new material system is still a challenge. In this study, Silver (Ag) nanofluids as kinetic promoter of sulfur hexafluoride (SF6) hydrate were prepared by electrical explosion of pure metal wire in deionized water. The kinetics of SF6 gas hydrates were evaluated with different concentration of Ag nanofluids at condition of 276 K and 0.7 MPa, respectively. The Ag nanofluids, as kinetic nano-prompter, showed excellent effect on the formation of SF6 hydrates.

Effect of the Length of the Interelectrode Gap during an Underwater Spark Discharge and the Length of a Conductor during Its Underwater Electrical Explosion on the Amplitude of the Generated Pressure Wave

Experimental results on the effect of the length of the discharge gap during an underwater spark discharge and the length of the metal conductor at its underwater electrical explosion are presented. In both cases, the dependence of the pressure wave amplitude on the length of the interelectrode gap or the conductor length has an optimum at which the pressure wave with a maximum amplitude is generated. In this respect, it is necessary to realize the modes with an optimal value of the length of the interelectrode gap, which ensures the efficient electrodischarge effect on the object treated. During the underwater spark discharge, it also allows realizing the mode close to critical, which positively affects the resource and lifetime of the electrodischarge equipment. It is shown that the change in the length of the metal conductor at its underwater explosion with the invariable parameters of the discharge circuit changes the mode of the underwater electrical wire explosion.

Dimensional effects of electrically exploding aluminum wires in argon gas: Experimental investigation

The strong dependence of electrical explosion of wires (EEW) on wire dimensions is demonstrated experimentally from three perspectives: electrical characteristics, spatial structures, and nanopowder properties. Electrical characteristics of EEW were explored by measuring current and voltage waveforms of exploding 20–100 μm-diameter and 2–10 cm-long wires in argon gas. The discharge mode, energy deposition, and breakdown characteristics of EEW were analyzed based on the calculation of several electrical parameters. Laser-based diagnostics and multi-frame photographs were used to obtain the EEW spatial structures and their evolutionary characteristics. The radial distribution of exploding wires in the early and diffusion stages was obtained according to the analysis of shadowgraphs and interference images. The optical observations suggested that nonuniformity of EEW spatial structures becomes appreciable with the increase of wire dimensions. Inhomogeneities in exploding wires (e.g., residual cores, gaps, local hot spots, and stratification phenomena) and the causes of their formation were also discussed. The morphology and particle size distribution of nanopowders produced by EEW were also observed via transmission electron microscopy as well. The statistical results show that increasing wire dimensions (diameter and length) increase the average diameter and broaden the size distribution of nanopowders.

Electrical explosion of nickel wire as an efficient method for large-scale preparation of nickel oxide nanopowders: evaluation of operational key factors on the average crystallite size and average size distribution using response surface methodology (RSM)

The electrical explosion of wire (EEW) method provides a sufficiently route for large-scale preparation of nickel oxide nanopowders (NiO-NPs) with a small degree of contamination. In this study, Central composite design of the response surface methodology (RSM) was firstly employed to evaluate the average crystallite size (ACS) and average size distribution (ASD) of NiO-NPs. Twenty types of NiO-NPs were prepared by adjusting three operating parameters (wire diameter, the distance between two electrodes and the voltage) at five levels by the method of multiple variable analysis. The check experiments revealed that all the three operating parameters have significant effect on the ACS and ASD of NiO-NPs. For each response, a suitable second-order regression equation was obtained by applying analysis of variance. In addition, the results revealed acceptable agreement among experimental data and predicted results. Moreover, the optimum region for production of NiO-NPs with size below 100 nm by EEW method was obtained. Characterization of NiO p-type semiconductor in terms of size distribution, morphology, chemical composition and phase structure was carried out by TEM, SEM/EDX, XRD and BET analyses. The results nominated the EEW technique as a unique method for large-scale and economic preparation of NiO-NPs with defined structural features.