Wire Electrical Explosion Method Research Articles

Peroxymonosulfate activation by carbon-encapsulated metal nanoparticles: Switching the primary reaction route and increasing chemical stability

This study explores the technical merits of carbon encapsulation via an electrical wire explosion method to enhance the peroxymonosulfate activation performance of metals. Reflecting the nature of core-shell structures, the outer carbon layers hampered the reductive conversion of peroxymonosulfate to sulfate radicals by the inner metal cores, whereas the metal cores increased the overall electrical conductivity as a pivotal factor in non-radical activation. Hence, the impact of carbon wrapping hinged on the peroxymonosulfate reduction capability of the metals, i.e., kinetic retardation in organic degradation with reactive Cu, Fe, and Ni-Fe, but acceleration with unreactive Ni. Further, composite fabrication switched the major degradative pathway from radical-induced oxidation to mediated electron transfer, as determined from the effects of methanol and chloride, formaldehyde and bromate formation yields, reactivity toward multiple organics, and electron paramagnetic resonance spectral features. The protective carbon shells enabled pH-insensitive peroxymonosulfate activation, prevented metal ion leaching, and alleviated catalyst deactivation.

A Spectroscopic and structural study of FeCoSb alloy

Fe, Co and Sb nanopowders were fruitfully prepared by electrical wire explosion method in Double distilled and de-ionized water (DDDW) media. The formation of iron, cobalt and antimony (FeCoSb) alloy nanopowder was monitored by X-ray diffraction. The x-ray diffraction pattern indicates that there are iron, cobalt and antimony peaks. Optical properties of this alloy nanoparticles were characterized by UV-Visible absorption spectra. The absorption peak position is shifted to the lower wavelengths when the current increases. That means the mean size of the nanoparticles controlled by changing the magnitude of the current. The surface morphological analysis is carried out by employing Scanning Electron Microscope (SEM). Particles with varies size were observed also from the images the some particles have uneven shapes with agglomerate and the other have spherical shape. The exploding FeCoSb alloy wire plasma parameters is study by optical emission spectroscopy. The emission spectra of the plasma have been recorded and analyzed. The plasma electron temperature (Te), was determined by Boltzmann plot, and the electron density (ne), by Stark broadening for wire with diameter 0.3 mm and current of 75A in distilled water.

Using Nickel Nanopowders with Different Morphologies for Fabrication of Highly Porous Nickel Materials

We study the effects that the morphology of nickel nanopowders obtained by chemical metallurgy, nickel formate thermal decomposition, and wire electrical explosion has on the properties of porous samples fabricated from these nanopowders using the powder metallurgy method. Porous nickel samples are prepared from a mixture of nickel powder (30 vol %) and ammonium bicarbonate (70 vol %) by sintering in a flow of hydrogen at 700°C and under a pressure of 300 MPa. Samples fabricated from the nickel nanopowder obtained by the wire electrical explosion method have the highest total and open (65.8%) porosities. Samples fabricated from the other two types of nickel nanopowders have lower porosity.

Fabrication of Sn–58Bi–xCe Solder Paste Using Electrical Wire Explosion Method and its Mechanical Property

Fabrication of Sn–58Bi–<i>x</i>Ce Solder Paste Using Electrical Wire Explosion Method and its Mechanical Property

Dispersion Stabilities of Multi-Layer Graphene-Coated Copper Prepared by Electrical Wire-Explosion Method

Dispersion Stabilities of Multi-Layer Graphene-Coated Copper Prepared by Electrical Wire-Explosion Method

Study on Characteristics of Nanopowders Synthesized by Nanosecond Electrical Explosion of Thin Aluminum Wire in the Argon Gas

As a new gas-phase synthesis method for the production of nanosize powders, the wire electrical explosion method has the advantages of high energy efficiency and high product purity through production under pure inert gas conditions and has been applied to the continuous industrial production of nanopowders. In this paper, an experimental device based on the electrical explosion of metallic wires for nanopowder production and collection is designed and built. Also, aluminum nanopowders were produced by electrically exploding an aluminum wire and collected by the microporous membrane filter successfully under different pressures of argon gas. Moreover, the influence of the argon gas pressure on the characteristics of the aluminum nanopowders was analyzed by a transmission electron microscope. The results showed that the particle shape, size, and distribution of the aluminum nanopowders could be controlled by the pressure of argon gas. The aluminum nanoparticles produced in the high-pressure argon gas had better spherical particle shape; meanwhile, the count mean diameter of the aluminum nanopowders increased obviously with the rise of the argon gas pressure. A higher pressure of argon gas could broaden the range of the aluminum nanoparticle size distribution evidently.

정전 분무 공정을 이용한 Fecralloy 나노 입자가 코팅된 Fecralloy Foil의 제조

Fecralloy is the promising materials for high temperature exhaust filtering system due to the excellent its oxidation resistance property. In this research, Fecralloy nanoparticles coated Fecralloy thin foil was prepared by a single nozzle electrospray system in order to increase surface area of Fecralloy foil. Fecralloy nanoparticles were fabricated by electrical wire explosion method in ethanol using Fecralloy wires as a source material. Electrospray modes with applied D.C voltages to Fecralloy colloidal solution were investigated to make a stable cone-jet mode. Coated layers with and without additional heat treatment were observed by FE-SEM (field emission-scanning electron microscope) and tape test for evaluating their adhesion to substrate were performed as well.

Rapid Consolidation of Nanostuctured TiCu Compounds

TiCu nanopowder was produced using an electrical wire explosion method and subsequently consolidated into dense nanostuctured TiCu by a high frequency induction heated sintering method. The consolidation was accomplished by the combination of an induced current and a high mechanical pressure within two minutes. This process results in very quick densification to near the theoretical density and prohibits grain growth in nano-structured materials. The grain sizes and mechanical properties of the sintered TiCu were investigated.

Characteristics of Fe-Cr-Al Alloy Nanopowders Prepared by Electrical Wire Explosion Process under Liquid Media

Fe-Cr-Al alloy nanopowders were successfully prepared by electrical wire explosion method in ethyl alcohol media. The formation of Fe-Cr-Al alloy nanopowder was monitored by X-ray diffraction. The alloy powders have spherical shape and nanometer size. The alloy powders prepared by the electrical wire explosion method have main crystal structures of bcc Fe-Cr alloy. The geometric mean diameter and geometric standard deviation of an alloy powder formed from a wire with diameter of 0.1 mm were 10.2 nm and 1.62, respectively. However, the geometric mean diameter and geometric standard deviation of an alloy powder formed from a wire with diameter of 0.2 mm were 15.4 nm and 1.66, respectively. These values indicate that the particle size of the alloy powders prepared by the EWE method was increased with wire diameter. Fe, Cr, and Al components are uniformly dispersed inside the powder.

Quench collection of nano-aluminium agglomerates from combustion of sandwiches and propellants

An experimental investigation has been carried out to measure the size of nano-aluminium agglomerates emerging from the combustion of nano-aluminized sandwiches and composite solid propellants. Nano-aluminium of median size of 50 nm produced in-house by the electrical wire explosion method is used in these samples. Propellants with different sizes of coarse and fine ammonium perchlorate are considered. Surface features of sandwiches and a propellant whose burning was interrupted by rapid depressurization are examined in a scanning electron microscope. The combustion products of the sandwiches and propellants are quenched close to the burning surface and collected in a quench collection set-up. The surface features of rapid-depressurization quenched sandwiches exhibit relatively large nano-aluminium clusters—of the order a few micrometres—particularly in the binder lamina. Quench-collected nano-aluminium exhibits significant agglomeration, but only a small fraction of the agglomerates are in the 1–3 μm range, except for both the coarse and fine AP particles used in the formulation being large, but even there they do not exceed ∼5 μm in size. This is expected to be benign for reduced smoke propellant applications from exhaust signature point of view, and to decrease the specific impulse losses without sacrificing the energetics of the propellant.

Activation and Gas Sorption Properties of Nano-Size Titanium Powder Getters

Non-evaporable getters (NEGs) are characterized by two major properties i.e. the activation and gas sorption rate for specific gases. Most of the commercial getters are alloys composed of micron-size powders. There have been speculations on the advantage of using nanosize powders as getter material for the obvious increase in volume to surface area ratio and for effective reaction with gases on size reduced particles. In this study, titanium powders of about 80 nm were prepared by electrical wire explosion method and their gettering properties were measured in accordance to ASTM standard. The activation of nano-size titanium powders was completed at about 450oC and the sorption rate was over 4 times higher than those of the micron-size titanium powders.

Simple synthesis and characteristics ofMo/MoS2 inorganic fullerene-like and actinomorphic nanospheres with core–shell structure

High yields of Mo/MoS2 inorganic fullerene-like and actinomorphic nanospheres with a core–shell structure havebeen successfully synthesized by the one-step reaction of sulfur and molybdenumnanospheres under a hydrogen atmosphere, in which the Mo nanosphereswere prepared by the wire electrical explosion method. The shell thickness ofMoS2 is about 4–10 nm and exhibit an expansion of about 4.2–1% along thec-axis. Observed from high-resolution transmission electron microscopyimages, unreacted molybdenum lying between the (002) layers ofMoS2 contributes to the larger expansion besides the strain in the bentlayer and the crystal defects; the preferred growth orientations forMoS2 on the surface of Mo have two directions under different annealing temperatures: parallel tothe (110) plane of Mo, presenting an actinomorphic phase, and perpendicular or havingcertain angles to the (110) plane, showing a fullerene-like phase. The actinomorphicMo/MoS2 can be used for catalysis and intercalation. The fullerene-like phase can be applied as asolid lubricant to enhance the structural rigidity and load bearing capacity of hollowMoS2. In addition, the core–shell nanospheres exhibit a little higher onset temperature and a narrowtemperature range against oxidation with a weaker exothermic peak than conventional2H-MoS2.

Synthesis and thermal stability of W/WS2 inorganic fullerene-like nanoparticles with core–shell structure

W/WS2 inorganic fullerene-like (IF) nanoparticles with core–shell structure are synthesized by the reaction of tungsten nanospheres and sulfur at relatively low temperatures (380–600°C) under hydrogen atmosphere, in which tungsten nanospheres were prepared by wire electrical explosion method. Images of transmission electron microscopy and high-resolution transmission electron microscopy show that the composite particles are of core–shell structure with spherical shape and the shell thickness is about 10nm. X-ray powder diffraction results indicate that the interlayer spacing of IF-WS2 shell decreases and approaches that of 2H-WS2 with increasing annealing temperatures, representing an expansion of 3.3–1.6%. A mechanism of IF-WS2 formation via sulfur diffusion into fullerene nanoparticles is discussed. Thermal analysis shows that the nanoparticles obtained at different temperatures exhibit similar thermal stability and the onset temperature of oxidization is about 410°C. Encapsulating hard tungsten core into IF-WS2 and the spherical shape of the core–shell structures may enhance their performance in tribological applications.

Preparation and characteristics of core–shell structure nickel/silica nanoparticles

The spherical nickel nanoparticles (an average diameter of 75 nm) were prepared by wire electrical explosion method, and silica was coated on nickel forming complete coverage by the controlled hydrolysis and condensation of tetraethyl orthosilicate (TEOS). The method was based on the use of silane coupling agent 3-mercaptopropyltrimethoxysilane (HS-(CH 2) 3Si(OCH 3) 3, MPTS) as a primer to render the nickel surface vitreophilic, thus rendering nickel surface compatible with silica. The thickness of SiO 2 coating layer increases with the increasing reaction time. The nickel nanoparticles and the nickel coated with silica shell were confirmed by transmission electron microscopy (TEM). X-ray photoelectron spectroscopy (XPS) was used to gain insight into the way in which the MPTS is bound to surface of the nickel nanoparticles. Result of the thermogravimetric analysis (TGA) and differential thermal analysis (DTA) indicate that the thermal stability of nickel/silica is better than of pure nickel nanoparticles. Magnetic properties of these powders have been evaluated. These nickel/silica core–shell nanoparticles can be utilized as precursors for making property-tunable magnetic nanoparticles, thin films, and multilayered core–shell structure nanocomposites.

Kinetic and Thermodynamic Features of Combustion of Superfine Aluminum Powders in Air

An experimental study on the combustion of superfine aluminum powders (average particle diameter, a<TEX>$_{s}$</TEX>: ∼0.1 <TEX>${\mu}{\textrm}{m}$</TEX>) in air is reported. The formation of aluminum nitride during the combustion of aluminum in air and the influence of the combustion scenario on the structures and compositions of the final products are in the focus of this study. The experiments were conducted in an air (pressure: 1 atm). Superfine aluminum powders were produced by the wire electrical explosion method. Such superfine aluminum powder is stable in air but once ignited it can burn in a self-sustaining way due to its low bulk: density (∼0.1 g/㎤) and a low thermal conductivity. During combustion, the temperature and radiation were measured and the actual burning process was recorded by a video camera. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and chemical analysis were performed on the both initial powders and final products. It was found that the powders, ignited by local heating, burned in a two-stage self-propagating regime. The products of the first stage consisted of unreacted aluminum (-70 mass %) and amorphous oxides with traces of AlN. After the second stage the AlN content exceeded 50 mass % and the residual Al content decreased to ∼10 mass %. A qualitative discussion is given on the kinetic limitation for AlN oxidation due to rapid condensation and encapsulation of gaseous AlN.N.

Application of Nanodispersed Powders Produced by Wire Electrical Explosion Method

In the present work some properties of nanopowders and possible areas of their applications are discussed. Main attention is paid to the use of nanodispersed powders (NDP) in new materials production technologies.

Preparation and characterization of nanocrystalline powders of Cu–Zn alloy by wire electrical explosion method

Nanocrystalline particles of Cu–Zn alloy in the size range from 10 to 140 nm with a mean particle size of 85 nm have been prepared from α-Cu–Zn alloy wire containing 39.8 at.% Zn by a wire electrical explosion method by adopting appropriate process parameters. The particles are identified as a mixture of α, β, γ, and ε phases of Cu–Zn alloy from X-ray powder diffraction (XRD). Most of the powders are hexagonal in shape, with only a small part being spherical and cubic. The particle size of the product obeys the log-normal distribution law, which indicates that the formation of particles with different sizes corresponds with probability dynamics. A possible mechanism for the formation of the alloy nanoparticles is proposed.

One-step synthesis of the nanometer particles of γ-Fe 2O 3 by wire electrical explosion method

Nanoparticles of γ-Fe 2O 3 with a mean particle size of 9 nm (an average nanograin size of 4 nm) have been prepared by an electrical explosion method through one-step. The particles were nearly equiaxed. The particle size distribution fits with log-normal distribution law as identified by SAXS. The coercivity and the saturation magnetization of the sample were determined to be as about 30% of those of the bulk materials by VSM. A possible mechanism for the formation of the γ-Fe 2O 3 was proposed.

Fabrication of Core-Shell Structured Ni-Based Alloy Nanopowder by Electrical Wire Explosion Method

&lt;p&gt;Electrical wire explosion in liquid media is a promising method for producing metallic nanopowders. It is possible to obtain high-purity metallic nanoparticles and uniform-sized nanopowder with excellent dispersion stability using this electrical wire explosion method. In this study, Ni-Fe alloy nanopowders with core-shell structures are fabricated via the electrical explosion of Ni-Fe alloy wires 0.1 mm in diameter and 20 mm in length in de-ionized water. The size and shape of the powders are investigated by field-emission scanning electron microscopy, transmission electron microscopy, and laser particle size analysis. Phase analysis and grain size determination are conducted by X-ray diffraction. The result indicate that a core-shell structured Ni-Fe nanopowder is synthesized with an average particle size of approximately 28 nm, and nanosized Ni core particles are encapsulated by an Fe nanolayer.&lt;/p&gt;