Wire Explosion Process Research Articles

The structural characteristics of nano-copper thin films produced via laser-assisted electric wire explosion process

Abstract Due to the wide range of important applications, the metal and metal oxide nanoparticles have increasing demand, so that many methods and technologies attempted to produce it. The Electric Wire Explosion (EWE) method is the most established method to produce nanometals and metal oxides in the form of either powders or thin films. In this study, copper and copper oxide films were prepared via electric wire explosion method with a developed laser igniting spark gap switch. The Cu thin films were prepared at different explosion voltages (4, 5 and 7kV) and then their structural properties were studied. The results show that the produced copper/copper oxides nanoparticles of thin films increased as the exploding voltage increased. The XRD test shows that the films crystallite size increased as the exploding voltage increased. FE-scanning electron microscope (FE-SEM) images, are shows the decrease of grain size of thin films as the explosion voltage increase.

Research on the sub-millisecond underwater electrical wire explosion process

Abstract Underwater electric wire explosion (UEWE) has great potential as a shockwave source for medical and industrial applications. This paper focuses on the process of the sub-millisecond underwater electrical wire explosion (smUEWE). The study compared the smUEWE and the microsecond underwater electrical wire explosion, which revealed the occurrence of partial vaporization under smUEWE, leading to the formation of bamboo-shaped cavities and frontal shock waves. The experiments of smUEWE were carried out under different stored energy, the results indicated the plasma shrinkage and cavity separation during the overall ionization process. Additionally, the study observed secondary breakdown caused by the uneven distribution of ionization products. An analysis was conducted on smUEWE considering partial vaporization, which divided the electrical explosion into a positive feedback process which promoted the axial instability and a negative feedback process which formed the uniform plasma channel. The analysis results was consistent with the experimental results.

Single step synthesis of WO3 nanoparticles by wire explosion process and its photocatalytic behaviour

Tungsten (W) wires are exploded in oxygen ambience to get tungsten oxide (WO3) nanoparticles (NPs). Energy stored in the capacitors (EC) is used to overcome the sublimation energy of wire. Energy ratio (K, ratio of EC and sublimation energy) and oxygen pressure (P) are two control parameters for the particle phase and morphology in the wire explosion process. X-ray diffraction (XRD) patterns confirmed the partial oxidation of W for low values of K. For K = 2, oxidation increases with increase in P. For K = 10, complete oxidation was achieved irrespective of P. Particles are spherical in shape as observed from scanning electron microscope (SEM) and transmission electron microscope (TEM) micrographs. Particle size follows a log-normal distribution with a least mean size of 24.1 nm. UV-vis diffuse reflectance spectroscopy (DRS) was used to measure the absorbance of NPs (complete WO3 with least mean size) for band gap measurement. The band gap was found to be 2.92 eV (visible region). NPs are used as photocatalyst to degrade aqueous solution of methylene blue (MB) under visible light irradiation. 500 mg l−1 of WO3 NPs were optimum to degrade 10 mg l−1 MB in 120 min.

Anomalous magnetic behavior in Ni80Cr20 nanoparticles prepared by physical and chemical methods

We report a detailed study of the structural and magnetic properties of Ni80Cr20 fine particles prepared by physical methods, such as mechanical alloying, wire explosion process (WEP), and chemical methods like sodium borohydride reduction, polyol method. From the analysis of structural and microstructural data, phase formation with the desired composition is confirmed in the particles prepared by the WEP. A comparative study of magnetization data of bulk and nanoparticles of Ni80Cr20 suggests that a weak magnetic moment develops in nanoparticles due to finite-size effects. Analysis of magnetization data suggests a superparamagnetic (SPM) behavior in the smallest sized (34 nm) particles prepared by WEP, while nanoparticles prepared by other methods show ferromagnetic ground state. Further, it is shown that the origin of weak magnetic moment and development of SPM state in the nanoparticles is due to uncompensated surface spins with a negligible interaction effect.

Experiments on the characteristics of underwater electrical wire explosions for reservoir stimulation

Underwater shock waves generated by pulsed electrical discharges are an effective, economical, and environmentally friendly means of stimulating reservoirs, and this technology has received much attention and intensive research in the past few years. This paper reviews the main results of recent work on underwater electrical wire explosion (UEWE) for reservoir stimulation. A platform is developed for microsecond single-wire explosions in water, and diagnostics based on a voltage probe, current coil, pressure probe, photodiode, and spectrometer are used to characterize the UEWE process and accompanying shock waves. First, the UEWE characteristics under different discharge types are studied and general principles are clarified. Second, the shock-wave generation mechanism is investigated experimentally by interrupting the electrical energy injection into the wire at different stages of the wire-explosion process. It is found that the vaporization process is vital for the formation of shock waves, whereas the energy deposited after voltage collapse has only a limited effect. Furthermore, the relationships between the electrical-circuit and shock-wave parameters are investigated, and an empirical approach is developed for estimating the shock-wave parameters. Third, how the wire material and water state affect the wire-explosion process is studied. To adjust the shock-wave parameters, a promising method concerning energetic material load is proposed and tested. Finally, the fracturing effect of the pulsed-discharge shock waves is discussed, as briefly are some of the difficulties associated with UEWE-based reservoir stimulation.

Dynamical aspects of nanoparticle formation by wire explosion process

Copper nanoparticles (NPs) were produced by wire explosion process (WEP) and it was noted that the amount of energy (E) deposited on the wire and the ambient pressure play a major role on the size of particles formed. Dynamic diffusion and condensation processes of NPs formation by WEP were modelled. Calculations of critical size of embryo, activation energy and nucleation rate of the formation of NPs in WEP were made considering classical homogeneous nucleation theory. Decrease in critical size of nuclei and activation energy, increase in nucleation rate with high E (540 J) and low operating pressure (10 kPa) confirm the formation of small size NPs (26 nm). Different cooling rates due to unsymmetrical shape of the vapour cloud has been identified as the cause for generating mixed particle sizes. The qualitative analysis conducted in this work validates the obtained experimental results and can be used as a design tool for industrial apparatus to produce NPs in bulk.

Effects of water states on the process of underwater electrical wire explosion under micro-second timescale pulsed discharge

This paper studied the influence of water parameters on the behaviour of an electrical wire explosion. In the experiments, a Cu wire of four sizes was exploded in water medium with different conductivity, hydrostatic pressure, and temperature. Under three typical discharge types, the electrical characteristics, shock wave, and optical emission phenomena were obtained and analysed. It has been found that the ambient medium changed the wire explosion process via adjusting the energy deposition or suppressing the later cavity expansion. Furthermore, wire explosion and its accompanied phenomena could be regulated based on the shunt effect. Finally, the mechanisms of the influence of water medium on a water gap breakdown and wire explosion were compared, and possible applications discussed.

Synthesis and characterization of hypoeutectic Al-Mg nano powder produced by electrical explosion method

Hypoeutectic composition of Al-Mg alloy binary system was established as a stabilized composition for production of Al-Mg alloy nano powders for fabrication of solid propellant. Nano powder of hypoeutectic Al-Mg alloy was prepared by high voltage Electrical Wire Explosion Process (EEW) under inert Argon and Helium gas environment with chamber pressure of 25 kPa and 50 kPa. The thin wires for explosion were prepared by Electrical Discharge Machining (EDM) process from Al-Mg alloy cast. XRD analysis of powder produced and alloy cast was performed to compare the phases present. Scanning Electron Microscope (SEM) images were taken for studying the shape and structure of the nano powder particles and Energy Dispersive Analysis of x-rays (EDX) was performed for affirming elemental composition of alloy powder. Morphological characteristics of nano powders were analyzed by Transmission Electron Microscope (TEM) images and the particle diameter was found ranging from10 nm to 90 nm. Highly magnified TEM images were obtained to analyze the formation of various phases in the powder. Thermo-Gravimetric Analysis and Differential Scanning Calorimetry (TGA-DSC) measurements were made to substantiate the low melting nature of Al-Mg alloys predicted by Al-Mg binary phase diagram with an offset temperature of melting 460 °C, which is much closer to the eutectic melting point (450 °C) of Al-Mg binary metal alloy. With the improved ductility of hypoeutectic alloys enabling better machinability to produce thin wires than eutectic composition, the results suggests hypoeutectic nano powders can be used as replacement for nano aluminium as energetic element in solid propellants.

Formation of tungsten carbide nanoparticles by wire explosion process

AbstractTungsten carbide nanoparticles (NPs) were synthesized by wire explosion process (WEP) in gas ambient as carbon source. Formation of tungsten carbide (WC1−X) in a single step by WEP using methane and argon‐acetylene mixture as carburizing medium, is detailed. X‐ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to observe the phase and morphology of the produced NPs. In WEP, morphology and phase of NPs are controlled using different levels of energy ratio, K (ratio of energy supplied to wire and sublimation energy of wire), type and pressure, P of ambience. High purity WC1−X NPs was synthesized in methane ambience with a high K (=19) and a high P (270 kPa). A thorough study has been made to understand the impact of type of carburizing medium. Methane‐acetylene mixture gave two phases of carbides. Argon‐acetylene ambience provided complete carburization in specific cases. In general, the formed NPs are spherical in shape. Formation mechanism of tungsten carbide NPs is detailed in the work.

Synthesis of titanium carbide nanoparticles by wire explosion process and its application in carbon dioxide adsorption

Titanium carbide (TiC) nanoparticles have been synthesized by exploding titanium wire in methane as well as diluted acetylene atmosphere at different gas pressures. The synthesized samples have been annealed to enhance the level of carburization and to reduce the amount of excess amorphous carbon present on the surface of the as-synthesized nanoparticles. The crystallinity, surface morphology and surface area of the produced nanocarbide samples have been probed by various characterization techniques. The size of the carbide nanoparticles was measured using lognormal distribution derived from transmission electron microscopy analysis. An increase in the applied energy shows a significant reduction in particle size irrespective of the operating pressure. Further, TiC nanoparticles have been utilized to study the CO2 adsorption properties at different temperatures and in low pressure (≤1 bar). The synthesized nanoparticles may not show very high adsorption capacities, but significant enhancement in adsorption has been observed when compared to bulk TiC. The isosteric heat of adsorption was determined from the variation of pressure with temperature at a constant excess gas uptake. The standard enthalpy change (ΔH) observed during adsorption manifests that the adsorption process in TiC is exothermic and within the range of physisorption such that the gas can be regenerated easily from the material utilizing minimum energy.

Enhancement of hydrogen generation using nanoaluminum particles produced by a wire explosion process

Nanoaluminum particles were generated by a wire explosion process (WEP) in helium, argon, and nitrogen ambiences, by depositing energy equal to the vaporization energy of the conductor material volume. The size and shape of the generated nanoaluminum particles were analyzed using a transmission electron microscope (TEM). X‐ray diffraction (XRD) analysis was carried out to characterize the phase in nanoaluminum (Al) particles. Particle size distribution of the produced nano‐Al particles follows log‐normal distribution and the nanoparticles produced in helium were of smaller size compared to those produced in argon or nitrogen ambience. Hydrogen gas was generated on reacting aluminum nanoparticles with aqueous NaOH solution. It was observed that most of the oxides formed on reaction of Al and aqueous NaOH solution were bayerite at room temperature and boehmite at higher temperature. The formation of bayerite and boehmite was characterized using XRD and TEM studies. The reactions were also carried out at higher temperature to understand the hydrogen generation rate. Molarity of NaOH has a high influence on the rate of hydrogen generation. The rate constant of the reaction was calculated adopting the first order rate law for predicting the amount of hydrogen generation. Nickel (Ni) nanoparticles synthesized by WEP and copper sulfate (CuSO4) were used as catalysts and added to the reaction mixture of Al and aqueous NaOH solution to control the hydrogen generation rate. It was observed that the reaction rate of Al with NaOH medium has increased with the addition of CuSO4 and Ni nanoparticles due to the microgalvanic effect, thereby enhancing the hydrogen generation rate. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

One‐step synthesis of NiO nano‐photocatalyst by wire explosion process and its application in photocatalytic degradation of Methyl tert‐butyl ether

AbstractThe use of the gasoline additive methyltert‐butyl ether (MTBE) has caused serious concern about groundwater and surface water contamination. In this study, UV light/ NiO nano‐photocatalyst (NiONP) system was firstly used to degradation of MTBE in contaminated water. A low‐cost and environmentally clean exploded‐wire plasma technique based on cheap solid nickel source is developed for preparation of NiONP. Optical, magnetic and physicochemical properties were successfully characterized using DRS, VSM, XRD, SEM, EDX, TEM and BET techniques. The NiONP exhibits excellent photocatalytic degradation ability of MTBE. The degradation process was monitored during the photocatalytic reaction by gas chromatography‐mass spectrometry (GC‐MS). It has been found that MTBE undergoes a series of intermediate step, which leads to form a number of intermediate products, mainly acetone, formic acid and t‐butyl formate (TBF). According to the results of the intermediates determination, a possible pathway degradation of MTBE was also proposed.

Carbon Dioxide Adsorption of Zinc Oxide Nanoparticles Synthesized by Wire Explosion Technique

Anthropogenic sources emit carbon dioxide (CO2) that leads to global warming and greenhouse effect motivating research in reducing the concentration of CO2 gas in the atmosphere. One of the efforts is to develop novel nanomaterials for CO2 capture by adsorption. Herein, we have synthesized zinc oxide (ZnO) nanoparticles by wire explosion process (WEP) and used it for CO2 adsorption studies. The effect of charging voltage and chamber pressure on the morphology of ZnO has been investigated. The CO2 adsorption studies were carried on in the temperature range of 10–25 °C and for equilibrium pressure up to 1 bar. ZnO NPs have shown a CO2 adsorption capacity of around 0.4 mmol g−1 at 283 K and 1 bar equilibrium pressure. It has been demonstrated that the sample shows higher CO2 adsorption capacity as pressure increases and sample temperature decreases. Thermodynamic studies revealed that the adsorbed CO2 on ZnO NPs could be easily regenerated.

Synthesis and Photocatalytic Activity of Anatase/Rutile TiO2 Nanoparticles by Wire Explosion Process

TiO2 nanoparticles (NPs) of mixed phases, namely anatase and rutile were produced by Wire Explosion Process (WEP), in oxygen ambience of different pressures. K, the ratio of energy stored in the capacitor to the sublimation energy of the wire was used as another parameter to control the phase and morphology of the NPs. Synthesized particles were characterized by X-ray diffraction studies which indicated the presence of mixed phase of NPs. The rutile content increased with increase in K and/or with decrease of oxygen pressure, P. TEM micrographs showed the nanoparticles produced are spherical in shape and follows log-normal distribution. Mean particle size and band gap (measured by UV–Vis diffuse reflectance spectroscopy) decreased with increase in K and/or decrease in P. Photocatalytic degradation of methylene blue (MB) dye was tested with TiO2 NPs produced at two extreme conditions. The optimum concentrations of NPs were found for the degradation of MB.

Thermodynamic Modelling and Characterisation of TiO2 nanoparticles Produced by Wire Explosion Process

Reaction mechanism for formation of Titania (TiO2) nanoaparticles by Wire Explosion Process (WEP) is described. Titanium wire and oxygen gas were the starting materials for the experiment. Energy (E) stored in capacitor and oxygen pressure (P) were varied. Rutile content of TiO2 increases and particle size decreases with increase in E and/or decrease in P. Homogenous nucleation theory was used to predict the activation energy and nucleation rate which is used to elucidate the experimental results.

Suppression of Red Luminescence in Wire Explosion Derived Eu:ZnO

Europium oxide (Eu2O3) is coated on zinc (Zn) wire using the electrophoretic deposition process. The coated Zn wire is subjected to the wire explosion process (WEP) which is rapid (< 15 min), and chimie douce (soft chemical, low temperature), in nature; this results in the formation of Eu doped ZnO. The explosion chamber contains oxygen (99.9%) at atmospheric pressure. Electron micrographs indicate that the particle sizes are ∼ 80 nm. Diffractogram-based analysis suggests that the crystallite size is ~ 18–20 nm in the as-prepared doped ZnO nanoparticles. Electron paramagnetic resonance shows the presence of Zn vacancies and the cryo-photoluminescence spectrum indicates that Eu exists in the + 3 state. A combined Williamson–Hall plot and Kisielowski’s model based analysis indicates that Eu is a substitutional dopant in WEP derived Eu:ZnO particles. It is estimated that this material has ∼ 0.24 at.% doping. This analysis also shows that, unlike another popular material GaN, in the case of ZnO, Eu3+ strictly substitutes for Zn2+ (i.e., dopant replacing a cation–anion pair does not seem possible). It may be noted that Eu3+ in a suitable host is oftentimes reported to be an efficient luminophore. The IR spectra show a band shift from 486 cm−1 to 493 cm−1; with peak shifts from 436 cm−1 to 430 cm−1 in Raman spectra. These too indicate the presence of Eu in the samples. However, at room temperature, only green luminescence (centered at 534 nm) is observed from the sample indicating (1) high concentrations of OZn anti-site defects and Zn vacancies, and (2) concomitant quenching of the luminescence at room temperature. Our results suggest that WEP is viable for synthesizing rare earth doped ceramic materials. However, obtaining efficient phosphors using this approach will likely require, (1) reduction of defect densities, and (2) appropriate passivation using post-processing.

Mo-MoO3-graphene nanocomposites as anode materials for lithium-ion batteries: scalable, facile preparation and characterization

The development of high-performance anode materials, along with simple synthesis processes, is of main issues to replace the commercial graphite anode and to achieve practical applications of Li-ion batteries (LIBs). Herein, we report a facile, scalable preparation of multiple Mo-MoO3-graphene nanocomposites using a simple wire-explosion process, followed by heat treatment in air, and their electrochemical performance as anode materials of LIBs. In this process, Mo wire is electrically exploded in methanol containing graphene at room temperature, resulting in well-dispersed Mo nanoparticles anchored on graphene. Subsequently, partial oxidation of Mo nanoparticles to MoO3 is achieved at 300°C in air, forming Mo-MoO3-graphene nanocomposites. For comparison, Mo-MoO3 nanocomposites are also prepared under the same conditions, without using graphene. Systematic phase and microstructural characterizations of both nanocomposites, as well as the as-synthesized Mo nanoparticles, are investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Raman spectroscopy. Their Li-storage performances are also evaluated and compared. Since graphene acts as a mechanical support to prevent Mo nanoparticle aggregation, and both Mo nanoparticles and graphene play an important role in providing effective electron pathways between active MoO3 nanoparticles, Mo-MoO3-graphene nanocomposites exhibit the conductivity and Li+ diffusivity enhancements (3.35×10−14cm2s−1), and structural stability, resulting in not only enhanced cycling performance, with a reversible capacity of 611mA h g−1 after 50 cycles at a constant current rate of 0.1C, but also a better rate performance than Mo-MoO3 nanocomposites. These synergistic functions are responsible for the better Li-storage performance of Mo-MoO3-graphene nanocomposite, which can lead to the promising candidates for LIB anode materials.

Experimental verification of the vaporization's contribution to the shock waves generated by underwater electrical wire explosion under micro-second timescale pulsed discharge

This paper studies pressure waves generated by exploding a copper wire in a water medium, demonstrating the significant contribution of the vaporization process to the formation of shock waves. A test platform including a pulsed current source, wire load, chamber, and diagnostic system was developed to study the shock wave and optical emission characteristics during the explosion process. In the experiment, a total of 500 J was discharged through a copper wire load 0.2 mm in diameter and 4 cm in length. A water gap was installed adjacent to the load so that the current was diverted away from the load after breakdown occurred across the water gap. This allows the electrical energy injection into the load to be interrupted at different times and at different stages of the wire explosion process. Experimental results indicate that when the load was bypassed before the beginning of the vaporization phase, the measured peak pressure was less than 2.5 MPa. By contrast, the peak pressure increased significantly to over 6.5 MPa when the water gap broke down after the beginning of the vaporization phase. It was also found that when bypassing the load after the voltage peak, similar shock waves were produced to those from a non-bypassed load. However, the total optical emission of these bypassed loads was at least an order of magnitude smaller. These results clearly demonstrate that the vaporization process is vital to the formation of shock waves and the energy deposited after the voltage collapse may only have a limited effect.

Combustion mechanism of composite solid propellant sandwiches containing nano-aluminium

Combustion of sandwiches made of alternating laminae of ammonium perchlorate (AP) and a matrix of hydrocarbon binder mixed with fine AP and nano-aluminium particles is considered in the 1–12MPa pressure range. Companion non-aluminized sandwiches are studied for comparison. The nano-Al particles are produced from the electrical wire explosion process in the size range ∼45nm, and added to the matrix containing either 5 or 45µm AP particles. Three categories of middle lamina thicknesses—thin (100–170µm), intermediate (200–280µm), and thick (370–480µm)—are examined in all the sandwiches. High-speed high-magnification imaging of the combustion is performed, and surface profiles and features of quenched sandwiches are investigated, besides burning rate measurements. The sandwich burning rates are compared with those of the corresponding matrices and AP laminae burning alone as well. The results imply the close location of lamina leading edge flames (L-LEFs) over the lamina interface edges, leaving the outer AP laminae inclined steeply relative to the matrix middle lamina, in the nano-aluminized cases relative to the non-aluminized versions. This observation suggests that the L-LEFs control the burning rates of the sandwiches even in the case of the fast burning matrix that contains nano-Al. The non-aluminized sandwiches containing the 5µm AP show higher burning rates than their 45µm AP counterparts because of the enhanced heat feedback available to the matrix burning surface from the extended fuel-rich branches of adjacent L-LEFs in the former case. Therefore, the enhancement in burning rate is minimal with the inclusion of nano-Al in sandwiches with smaller fine AP size, whereas the nano-aluminized sandwiches containing larger fine AP particles exhibit such enhancement. These effects affirm previous results on propellants with smaller fine and coarse AP sizes, where the burning rate is not enhanced by nano-Al.

Generation and characterisation of nano iron oxide by wire explosion process: a thermodynamic approach

Iron oxide (Fe 2 O 3 ) nanoparticles were generated in a single step by wire explosion process (WEP). The influence of energy deposited to the exploding conductor and the ambient pressure on phase, size and shape of the particle were analysed. Oxygen is used as medium during wire explosion process to obtain iron oxide. The characteristics of the particles were analysed through WAXD and TEM. The thermodynamic aspects of nanoparticle formation by wire explosion process are detailed.