High-voltage Discharge Process Research Articles

Nanocomposite of Tin and Lead Oxides Prepared in Plasma of Pulsed High-Voltage Discharge Process: Synthesis and Electrochemical Characteristics

In the present paper, a composite containing mixed oxides of tin and lead has been synthesized by the method of pulsed high-voltage discharge. Material was characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis and transmission electron microscopy. The composite consists of SnO2 and PbO particles with an average size of ~350 nm, and SnPb2O4 nanowhiskers with size of 100 nm in diameter and few microns in length. The electrochemical performance of nanocomposite as a potential anode of lithium-ion battery has been investigated by the cyclic voltammetry and galvanostatic charge/discharge test in the potential range of 3.0–0.005 V. The reversible capacity of 821 mA·h/g was realized after 5-fold cycling at a current density of 100 mA/g. It was established that further cycling of the material is accompanied by a dramatic capacity fade: only 13 % of the initial capacity was obtained already after 10 cycles. The observed degradation in performance of nanocomposite results from its inability to compensate large lithiation/delithiation-induced volume expansion.

Compact electromagnetic pulse forming system based on the trigger vacuum switch

Electromagnetic pulse forming (EMPF) is a type of electromagnetic manufacturing technology which produces a powerful Lorentz force to change the shape or form of a work piece. In this paper, a 6.75-kJ/15-kV compact EMPF system based on the RVU-43 trigger vacuum switch is designed, fabricated and tested. The RVU-43 has good performance in a high-voltage discharge process that can withstand 25 kV and conduct 400 kA. A trigger source for the RVU-43 based on a pulse transformer and a solid-state switch can generate a rectangular trigger pulse of an adjustable amplitude of 0–5 kV and a pulse width of 0–5 μs. A simulation model is built in PSPICE to analyze the parameters affecting the performance of the EMPF. The results show that the system inductance can affect the peak current and the rise time, while the system resistance can affect the peak current. Connecting the capacitors in parallel, reducing the discharge loop area and designing a single-turn forming coil with a 30-degree field shaper are used to reduce the influence of the system parameters. The results of experiments for changing the shape of an aluminum alloy tube suggest that the EMPF system can form and process the metal tube successfully.

Efficient removal of phenol from aqueous solution by the pulsed high-voltage discharge process in the presence of H2O2

Efficient removal of phenol from aqueous solution by the pulsed high-voltage discharge process in the presence of H2O2

Nanotechnology of metal and non-metal joining

The development of electronics and high-voltage discharge process simulations facilitated the development of a new method of joining metals and non-metals in Russia. A prospective method has been proposed for joining materials with specific physical and mechanical properties under conditions of decreased temperature and pressure – welding with metallic inserts (foil). During controlled high-voltage discharge, the insert material quickly evaporates. Thus, the obtained metal vapours with high kinetic energy hit the surface of the materials being joined, where the crystallization process occurs. A thin layer of metal is created on the surface of the non-metal, tightly adhering to the substrate and with the same crystal lattice as the non-metal material. Joints of high durability are achieved due to this metallic interlayer. The marginal heating of the non-metal substrate is an important aspect of the process. The article presents some of the crystallographic aspects of metal and non-metal joining by means of surface metallization with metallic vapours obtained as a result of evaporation of the foil material following an electric discharge.

Effect of Pulsed High-Voltage Discharge Process Combined with H2O2 and Fe2+ on Degradation of Phenol

Effect of Pulsed High-Voltage Discharge Process Combined with H2O2 and Fe2+ on Degradation of Phenol

Non-thermal plasma-induced photocatalytic degradation of 4-chlorophenol in water

TiO 2 photocatalyst (P-25) (50 mg L −1) was tentatively introduced into pulsed high-voltage discharge process for non-thermal plasma-induced photocatalytic degradation of the representative mode organic pollutant parachlorophenol (4-CP), including other compounds phenol and methyl red in water. The experimental results showed that rate constant of 4-CP degradation, energy efficiency for 4-CP removal and TOC removal with TiO 2 were obviously increased. Pulsed high-voltage discharge process with TiO 2 had a promoted effect for the degradation of these pollutants under a broad range of liquid conductivity. Furthermore, the apparent formation rates of chemically active species (e.g., ozone and hydrogen peroxide) were increased, the hydrogen peroxide formation rate from 1.10 × 10 −6 to 1.50 × 10 −6 M s −1, the ozone formation rate from 1.99 × 10 −8 to 2.35 × 10 −8 M s −1, respectively. In addition, this process had no influence on the photocatalytic properties of TiO 2. The introduction of TiO 2 photocatalyst into pulsed discharge plasma process in the utilizing of ultraviolet radiation and electric field in pulsed discharge plasma process enhanced the yields of chemically active species, which were available for highly efficient removal and mineralization of organic pollutants.

Neck Formation and Growth in High-Voltage Discharge Forming of Metal Powders

AbstractA review is presented of the postulated neck formation and growth mechanisms involved in the high-voltage discharge process for forming high aspect ratio powder metallurgy bodies. Together with the results of recent work this allows a mechanism of liquid-phase weld formation and growth to be outlined which is confirmed by scanning electron micrographs of welds found with a variety of materials. PM/0202