Wire Explosion Research Articles

Peculiarities of electrophoretic deposition and morphology of deposited films in non-aqueous suspensions of Al2O3–Al nanopowder

The paper presents the results of a comprehensive study of the electrokinetic properties of non-aqueous suspensions of the Al2O3–Al nanopowder obtained by the method of electric explosion of wires (EEW) with 0.3 wt.% of metallic aluminum in its composition. The dependence of zeta potential on the concentration of the Al2O3–Al suspension is revealed. The nature of long-term changes in zeta potential and pH in suspensions is established. Appearance of bubbles in the deposited coatings due to the interaction of metallic aluminum particles with the liquid suspension medium during electrochemical reactions on the electrodes is defined as the main feature of the electrophoretic deposition (EPD) process in the Al2O3–Al suspensions. The influence of the suspension preparation method on the deposited coatings’ morphology is demonstrated.

Synthesizing multicomponent AlCrFeCuNi nanoparticles by joint electrical explosion of wires

For the first time, by the example of an AlCrFeCuNi alloy this research work shows the possibility of obtaining multicomponent metal nanoparticles using joint electrical explosion of wires made of different metals/alloys. The analysis of the structural-phase state of nanoparticles has shown that particles have lognormal distribution by size, and their number average size is 40 nm. The nanocrystalline structure of nanoparticles is represented by two phases based on BCC and FCC lattices. According to the research findings, joint electrical explosion of wires made of different metals and alloys is a promising technique for obtaining multicomponent metal nanoparticles.

Experimental study on crushing of concrete columns by high voltage pulse discharge

High voltage pulse discharge (HVPD) crushing tests were carried out on 30 concrete columns with section sizes of 400 mm × 400 mm, 500 mm × 500 mm, 600 mm × 600 mm and 700 mm × 700 mm respectively. Based on the comparative analysis of the electrohydraulic effect and the copper wire explosion on the fracture test of a concrete beam, the latter is determined as the optimal method. The parameters in the test of crushing concrete columns by HVPD include strength grade of concrete, column borehole aperture, hole spacing, discharge voltage and number of copper wires. Columns with sectional dimensions of 400 mm × 400 mm and 500 mm × 500 mm are arranged in single row boreholes, and columns with sectional dimensions of 600 mm × 600 mm and 700 mm × 700 mm are arranged in double rows of boreholes. The results show that the crushing effect of concrete columns increases obviously with the increase of discharging voltage and the number of copper wires, and slightly increases with the decrease of concrete strength. When other parameters are the same, the crushing effect of the concrete columns with hole diameter of 40 mm is better than that of the ones with hole diameter of 50 mm. The crack connectivity of concrete columns with hole spacing of 300 mm is similar to that of the ones with hole spacing of 400 mm. According to the test results, the mathematical expressions of the damage degree of concrete columns with single and double rows of holes (i.e., the width of concrete cracks around boreholes) and the output voltage, the number of copper wires and the strength grade of concrete are established respectively. In order to meet the needs of the project, the suggestion of further crushing construction combined with mechanical method was put forward

Anomalous transparency at 1064 nm of a freely expanding gas cylinder in vacuum during fast electric explosion of thin metal wires

Laser shadowgrams of exploding metal wires in a vacuum show the anomalous transparency of a completely evaporated wire core for a probe beam with a wavelength of 1064 nm. Simultaneous shadowgrams at 532 nm show significant light attenuation. The anomalous transparency for laser radiation at a wavelength of 1064 nm is highly likely due to the Rayleigh scattering of the probing beam by metal atoms. Our experimental results can be explained under the assumption of a strongly non-equilibrium state of an expanding gas cylinder with a non-uniform density.

Synthesis of Ti–Al Bimodal Powder for High Flowability Feedstock by Electrical Explosion of Wires

In this research, Ti–Al bimodal powders were produced by simultaneous electrical explosion of titanium and aluminum wires. The resulting powders were used to prepare powder–polymer feedstocks. Material characterization involving X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and melt flow index (MFI) determination were carried out to characterize bimodal powders obtained and evaluate the influence of the powder composition on the feedstock flowability. The bimodal distribution of particles in powders has been found to be achieved at a current density of 1.2 × 107 A/cm2 (the rate of energy input is 56.5 J/μs). An increase in the current density to 1.6 × 107 A/cm2 leads to a decrease in the content of micron particles and turning into a monomodal particle size distribution. The use of bimodal powders for powder–polymer feedstocks allows to achieve higher MFI values compared with monomodal powders. In addition, the use of electroexplosive synthesis of bimodal powders makes it possible to achieve a homogeneous distribution of micro- and nanoparticles in the feedstock.

Iron Nanoparticle Production by the Method of Electric Explosion of Wire

Background: The widespread use of iron nanopowders is connected with a wide range of characteristics such as size, magnetic characteristics and high surface area and that is why many researches present its different applications in the literature. Objective: The work studies the influence of the conditions for the iron wire electrical explosion on the course of the explosion process and the dispersed composition of the resulting metal nanopowder. Method: Experiments on the electrical explosion of iron wires were carried out in the laboratory setup with the different initial conditions of the electrical explosion of the iron wire. Results: The influence of the initial wire electrical explosion conditions on the explosion regime, the specific energy input into the conductor, and the specific energy released in the arc stage of discharge are definitely determined. The empirical equations for the calculation of the initial wire electrical explosion conditions for providing the critical explosion in the argon medium at a pressure of 2·105 Pa, were defined. It has been established that for the synthesis of iron nanopowders with a narrow particle size distribution, it is preferable to use modes with a high level of the energy released in the arc stage of the discharge. Conclusion: It was found that disabling the arc stage of the discharge during EEW leads to the decrease of the average surface particle size by 50%.

Control of cluster coalescence during formation of bimetallic nanoparticles and nanoalloys obtained via electric explosion of two wires

In this study, the possibility of controlling the coalescence of clusters during the formation of bimetallic nanoparticles and nanoalloys is demonstrated for the first time using joint electric explosion of Nb/Al and Nb/Ag wires under an argon atmosphere as an example. The evolution of clusters in the condensed phase is considered based on the adiabatic approximation to expand the products of the electric explosion of wires. Controlling the temperature and size of the clusters formed under the electric explosion of wires generating the energy necessary for the transition from the metallic state to the two-phase state (clusters of the condensed phase and weakly ionized plasma) allows synthesizing nanoparticles and bimetallic nanoparticles possessing the structures of nanoalloys and Janus particles, respectively. The experimental studies are supplemented by describing structural patterns and segregation phenomena using a hybrid computer experiment that adopts two alternative methods, i.e., the Monte Carlo and molecular dynamics methods. Both methods predict similar structure formation trends, particularly segregation patterns, in Nb–Ag and Nb–Al nanoparticles. For the first time, we have obtained bimetallic nanoparticles possessing a more complex structure, compared to the formerly known core shell, namely the onion-like structure. The Nb2964–Ag2964 and Nb2964–Al2964 nanoparticles s are characterized by the formation of icosahedral cores and crystalline cores based on the hcp and fcc phases, respectively, over the entire temperature range studied.

Study on Breaking Concrete Structures by Pulse Power Technology

Using pulse power technology to break concrete structures can reduce environmental pollution, save energy, and increase safety and reliability. The whole process of concrete beam subjected to shock wave generated by pulse power discharge was simulated and analyzed. An experiment of breaking reinforced concrete beams by metal wire explosion in liquid was carried out. And the main parameters are pulse power discharge voltage, copper wires section size, concrete beam material strength, drilling parameters, etc. The results show that with the increase of discharge voltage and the total area of copper wire cross section between electrodes, the breaking effect of concrete beam is obviously improved. The breaking effect of the beam is slightly improved when the concrete strength is reduced. The breaking effect of concrete beams with 40 mm aperture is better than that of concrete beams with 50 mm aperture. As the distance between adjacent boreholes decreases, the fractures are easier to connect. According to the test results, the formulas for calculating the crack width of concrete beams were proposed, which takes the output voltage, the number of copper wires between electrodes, the hole spacing, the strength of concrete and other key parameters as independent variables. The calculated results agree well with the test results.

Development of Effectual Substrates for SERS by Nanostructurs-Coated Porous Silicon

The current paper provides an efficient method for making active and effectual substrates used for detecting molecules by improving surface-enhanced Raman scattering (SERS). These substrates were fabricated using nanostructure-coated porous silicon. The nanostructures were prepared through the electrical exploding wire (EEW) technique. The silver nanowires (AgNWs) were coated with a polydopamine (PDA) layer to form an AgNWs@PDA colloidal solution. Then, the Ag wire was electrically exploded in the colloidal solution to form the (AgNWs@PDA@AgNPs) plasmonic nanostructures as a metal-insulator-metal. The effect of the plasmonic nanostructures’ morphologies on the absorptances spectra and SERS activities were studied utilising Rhodamine 6G (Rh6G) dye as examination molecules. X-ray diffraction (XRD) was used to investigate the structural properties of these nanostructures. Field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were used to investigate the morphologies of these nanostructures. Atomic force microscopy (AFM) was used to study the surface topographies of SERS-effectual substrates. A double beam ՍV-Visible Spectrophotometer was used to measure Rh6G laser dye absorptance with a concentration of M) that mixed with the nanostructures at different concentrations. Sunshine Raman spectrometer with a (50 x) objective lens was used to analyse the Raman spectra of Rh6G Sunshine Raman spectrometer with a (50 x) objective lens was used to analyse the Raman spectra of Rh6G dye using a porous silicon substrate (PSi) on which silver nanowires are deposited (PSi-AgNWs). Another porous silicon substrate (PSi) on which nanostructures are deposited that consisting of silver nanowires, coated with a polydopamine layer, and decorated with silver nanoparticles are deposited (PSi-AgNWs@PDA@AgNPs). The results showed that hot spots and roughness on the nanostructures' surfaces caused an increase in intensities of absorptances spectra and signals of SERS. After the effectual substrates were excited by a (λexc.=532nm) laser source, the enhancement factor (EF) of SERS signals of Rh6G (1 M) attained (26.3 ) and (28.7 ) of the characteristic peaks at wavenumber (1650 ) for PSi-AgNWs and PSi-AgNWs@PⱰA@AgNPs effectual substrates respectively. This study showed that nanostructure-coated porous silicon substrates have a repeatable and high signal frequency, stability in storage, cost-low technique, and ease of use. They allow researchers to recognise and analyse a wide range of molecules, including biomolecules, with detection limits ranging between milli- and femtomolar. These effectual substrates have a bright future as a bioanalytical tool using SERS spectroscopy.

Synthesis of Titanium-Based Composites by Pulsed Methods

Ti-based composites with advanced properties were fabricated by the explosion of the wires and magnetic-pulsed compaction methods. After the wire explosion the “metal core – oxide (or nitride) shell” structure is formed. Magnetic-pulsed treatment of such poorly conductive powder leads to the destruction of the shells and to the appearance of an electrical conductivity. This conductivity is only 4-7 times higher than that of pure titanium. As a result of the dynamic compaction of 100-150 nm powder the hot-pressed Ti+9TiO2 composition appeared to have the best combination of mechanical properties: relative density – 95 %, microhardness - 4.2 GPa, reduced modulus of elasticity – 143 GPa, creep under constant load – 105 nm. The coefficients of thermal extension of three materials with different titanium oxide content: 6, 9 and 15 wt. % were measured. The nitride-containing composites were ~30% more porous and had low mechanical properties compared to Ti+TiO2 compacts.

Current distribution at underwater electrical explosion of wires with different diameter connected in parallel

Underwater electrical wire explosion is usually used as a source of underwater shock waves, and the generated shock wave intensity can be regulated by adopting a wire array. In this paper, the dynamics of the electrical explosion of two wires with different diameters connected in parallel were studied. The current flowing through each wire was measured to study the current distribution, and the self-emission image and laser backlight shadow image was obtained to observe the evolution of the wires. A numerical model was built to make explanations and predictions. The results showed that due to the presence of wire inductance and contact resistance between the wire and electrode, the wires are with different current densities and undergo asynchronous heating from the beginning of the discharge. Furthermore, the variation of current distribution among the wires was divided into six stages according to the moment the wire melted and exploded, and analyzed stage by stage. The unbalanced energy deposition results in obvious differences in thermal dynamic parameters, which explains the gradual “extinguishment” of the thinner wire in the self-emission image.

Coupling effect of side explosion vent and wire mesh on suppressing methane explosion in a closed duct

The coupling effect of the side explosion vent and wire mesh on suppressing methane explosion has been investigated in this study, aiming to prevent huge losses caused by a methane explosion in industrial organic waste gas treatment. It constructed a closed simulation duct with a length of 3000 mm and an internal dimension of 120 mm × 120 mm containing a side explosion vent at different positions, in which flame behaviours and overpressure characteristics accompanying methane explosion were analyzed to get conclusions. The results indicate that side explosion vents located in the same duct section have a similar explosive flame development trend, and the suppression effect is better as closer to the ignition source. Besides, it is necessary to avoid the redevelopment of flame and the backfire downstream of a side explosion vent. In addition, the overpressure released through side explosion vents is significantly suppressed. However, the wave-absorbing and heat-absorbing properties of the wire mesh installed in the duct are only effective for some configurations with low flame speeds. Moreover, the side explosion vent closed to the ignition source effectively suppresses undeveloped flame. In this case, it leads to a complete application of the porous media quenching performance. To sum up, the coupling suppression effect of the side explosion vent and wire mesh on flame is complementary. However, there is an opposite conclusion for the experimental configurations where side explosion vents are downstream of the duct; a high-speed turbulent flame is difficult to be suppressed by the wire mesh and side explosion vent in a flame acceleration mechanism.

Influences of the burden on the fracture behaviour of rocks by using electric explosion of wires

The burden is one of the most important parameters in the blasting operation of rock engineering, so it is essential to evaluate its influences on the fracture behaviours of rocks. In this work, blasting experiments on cement mortar samples were conducted with different burdens by taking the electric explosion of wires as the explosion source. Then, the fracture process of samples was revealed based on images captured by an ultra-high-speed camera. Changes in the scope of the fractured zone with the burden were quantitatively evaluated. Experimental results indicate that fractures on the free face are composed of transverse, longitudinal, oblique, and circular cracks. As the burden increases, the initiation time of cracks on the surface delays, accompanied by a decreased degree of fracturing on the free face. Meanwhile, the explosive load causes formation of a crater-shaped fractured zone in the samples. With the increase of the burden, the short axis, perimeter, and volume of the fractured zone all tend to increase, then decrease. The finite element program ANSYS/LSDYNA was used to perform numerical simulations. The simulation results were compared with the fracture mode of the free face and the fractured zone in samples in the experiments. Besides, the damage and fracturing patterns inside the samples were further investigated based on the numerical simulation results.

Experiments on plasma dynamics of electrical wire explosion in air

Besides a typical high-density plasma source, electrical explosion of conductors is also indispensable in switches, nanomaterial synthesis, shock-wave sources, etc. In this paper, an experimental study regarding plasma dynamics of electrical wire explosions (μs-timescale) is presented, with spatiotemporal resolved diagnostics. Pure Cu/Ni wire and Cu-Ni alloy wire were used and compared. The alloy wire usually has a higher resistivity, resulting in a higher initial energy deposition (heating) rate. Abel inverse transformation indicated that the plasma radiation focussed on the outer region of the discharge channel for the alloy wire. In addition, the metallic vapour determined by the material properties had a considerable influence on the plasma process and resulting nanomaterials. In particular, both transverse and axial-layered structures were observed in alloy wire vapour. In addition, for the first time, the expanding arc-like plasma of explosion products was understood and examined from aspects of material properties and energy relaxation. The later stage of wire explosion resembled the state of regular metal vapour arcs under 1 MPa pressure. Finally, the core factor for the fast energy deposition stage of wire explosion was ascertained. Correlations between pre-exposition circuit parameters and post-explosion dynamic effects were found, which is significant for practical applications.

Получение композиции ZnFe2O4/ZnO/ПММА с антибактериальными свойствами и низкой токсичностью

In present work, the possibility of obtaining ZnFe2O4/ZnO nanoparticles by electric explosion of zinc and iron wires in an oxygen-containing atmosphere is shown. Based on the obtained nanoparticles and polymethyl methacrylate, ZnFe2O4/ZnO/PMMA composite was obtained, containing from 0.5 to 10 wt. % of nanoparticles. The composite film suppressed the viability of E. coli bacteria with an efficiency of 99.99 %, which is due to the generation of reactive oxygen species. The synthesized composite material with high antibacterial activity is promising for the production of antimicrobial materials for medicine for a long time.

Применение ультразвуковой обработки для повышения фотохимической активности электровзрывных бикомпонентных наночастиц TiO2-Ag

TiO2-Ag nanoparticles with thermal and chemical stability, wide band gap and low toxic are more used photocatalysts for decomposition of organic substances. However, high rate of recombination of electron-hole pairs and high energy of photoactivation significantly limit their usage. Modification of TiO2 with silver promotes surface separation of charges and increases their photochemical activity. In the present study for obtain TiO2-Ag bicomponent nanoparticles was use electric explosion of metal wires in atmosphere 85 vol.% Ar - 15 vol.% O2. This method has a high productivity (170-200 g/h) which is enough for industrial application of nanoparticles. However, electroexplosive nanoparticles are mostly agglomerates with a size of 200-500 nm, which significantly reduces their photochemical activity in the test reaction of decomposition of the model dye methylene blue under the visible light radiation. Ultrasonic treatment of nanoparticles in aqueous suspension for 15 min. contributed to an increase in the photoactivity of TiO2-Ag nanoparticles by 10%

Forming and propagation of the cracks initiated with electric explosion of wires in polymer materials

Electrical-physical techniques of intensive mechanical action based in particular on the phenomenon of electric explosion of wires attract more and more attention as methods of high-rated deformation and fracture of polymer spacemen such as Poly(methyl methacrylate) (PMMA), fluoropolymer, etc. Detailed investigation of forming of cracks and dependence between it and propagation of the shock waves through the sample appears to be mandatory for the understanding of the processes of high-rated loading of such polymers.The study investigates forming of the cracks under the action of the cylindrical shock wave initiated with the electric explosion of wire. Generation of such wave performed with short intensive high-voltage discharge through the thin wire placed along we axis of the sample and subsequent expansion of its vaporization products. Propagation of such cracks through cylindrical samples of PMMA and fluoropolymer with various rates of loading was discovered. The comparative specifications of the development of the cracks in PMMA and fluoropolymer were obtained. Threshold fracture parameters of tested materials were estimated for various rates of stress. Analysis of correlation between parameters of the wire explosion and cracks forming and development performed.

Preparation of nano/micro-bimodal Ti/Al/(Mo, W, Cu) powders by simultaneous electrical explosion of dissimilar metal wires

Novel mixtures of micro- and nanoparticles have been obtained by simultaneous electrical explosion of three intertwisted wires (EEW). The possibility of obtaining of titanium‑aluminum micro- and nanoparticles alloyed with molybdenum, tungsten and copper by the electrical explosion of Ti/Al/(Mo, W, Cu – up to 6 at. %) wires has been shown. Spherical particle with sizes from 20 nm to 7 μm are formed under condition of introducing the electric energy at the level of 0.57–0.77 of the total sublimation energy. The mass content of particles with sizes less than 100 nm does not exceed 10%. The phase composition of powders includes double and triple intermetallic phases, titanium oxide (TiO) as well as phases of the initial metals. The study of the phase composition of bulk materials obtained by sintering powders Ti-Al-Mo, Ti-Al-W and Ti-Al-Cu for 2 h at 1000 °C showed the increase in the content of intermetallic phases, providing enhanced physical and mechanical properties of the titanium‑aluminum alloys. The results of the studies show that the obtained powders alloys can be used to produce feedstocks of TiAl alloys.

Adhesive and Magnetic Properties of Polyvinyl Butyral Composites with Embedded Metallic Nanoparticles.

Magnetic metallic nanoparticles (MNPs) of Ni, Ni82Fe18, Ni50Fe50, Ni64Fe36, and Fe were prepared by the technique of the electrical explosion of metal wire. The average size of the MNPs of all types was in the interval of 50 to 100 nm. Magnetic polymeric composites based on polyvinyl butyral with embedded metal MNPs were synthesized and their structural, adhesive, and magnetic properties were comparatively analyzed. The interaction of polyvinyl butyral (supplied as commercial GE cryogenic varnish) with metal MNPs was studied by microcalorimetry. The enthalpy of adhesion was also evaluated. The positive values of the enthalpy of interaction with GE increase in the series Ni82Fe18, Ni64Fe36, Ni50Fe50, and Fe. Interaction of Ni MNPs with GE polymer showed the negative change in the enthalpy. No interfacial adhesion of GE polymer to the surface of Fe and permalloy MNPs in composites was observed. The enthalpy of interaction with GE polymer was close to zero for Ni95Fe5 composite. Structural characterization of the GE/Ni composites with the MNPs with the lowest saturation magnetization confirmed that they tended to be aggregated even for the materials with lowest MNPs concentrations due to magnetic interaction between permalloy MNPs. In the case of GE composites with Ni MNPs, a favorable adhesion of GE polymer to the surface of MNPs was observed.

Measurement and interpretation of electrical signals in transient electrical discharges* *Also at ETSII C.Real, University of Castilla-la Mancha, Spain.

Electrical discharges in experiments like Exploding Wire, Plasma Focus, or Z-pinch, involve regions where strong transient electrical currents generates magnetic flux variations within the limits of experiment and diagnostics regions. Due to different experimental conditions, time duration of the transient phase may vary from negligible to play an important role in the explanation of the measured signal of the experiment, in which case Faraday’s law of induction cannot be neglected when analyzing the electrical signals. In this work the effects of circuit modeling taking into account Faraday’s law will be discussed for the exploding wire experiment in a more detailed way than previous works.