Arc plasma method

Arc Plasma Method The principle of NPs synthesis in this method is based on evaporation by heating and condensation by cooling. The bulk metal is evaporated by heating with electrical resistance, electron beam, or high-frequency magnetics, and subsequently the vapor of metal atoms is condensed on a substrate as a sohd film or particles. In the AP method, electrical charge filled in an external capacitor... 

Fig. 9.4.10 Apparatus for the gas flow-arc plasma method. The apparatus is composed of two components. The upper part is a glass Dewar, which accumulates small particles in a cryogenic matrix on the trim cooled with liquid nitrogen (LN). Sorv, inlet of organic vapor Syr, syringe for transferring produced colloids under anaerobic conditions RP, rotary pump S, target sample. Lower part is for plasma discharge. A BN furnace has gas inlets (G) and is specially designed for Ar gas to flow in screwed stream hence the plasma is emitted in a jet flame due to a plasma pinch effect. The black parts are copper electrodes cooled by water. In order to maintain a constant spacing between the surface of sample and tbe upper electrode, the sample position can move vertically so that the current through the sample to the upper electrode is precisely controlled and constant. This is very important to produce powders with a narrow size distribution.

Ohnishi R, Katayama M, Takanahe K, Kubota J, Domen K (2010) Niobium-based catalysts prepared by reactive radio-frequency magnetron sputtering and arc plasma methods as nonnoble metal cathode catalysts for polymer electrolyte fuel cells. Electrochim Acta 55 5393-5400... 

Ogumi, Z. Uchimoto, Y. Takehara, Z. Kanamoii, Y. (1989). Preparation of Ultra-Thin Solid-State Lithium Batteries Utilizing a Plasma-Polymerized Solid Polymer Electrolyte. /, Chem. Soc., Chem. Commun., Vol. 21, pp. 1673-1674 Ohnishi, R. Katayama, M. Takanabe, K Kubota, J. Domen, K (2010). Niobium-Based Catalysts Prepared by Reactive Radio-Frequency Magnetron Spnitteiing and Arc Plasma Methods as Non-Noble Metal Cathode Catalysts for Polymer Electrolyte Fuel Cells. Electrochim. Acta, Vol. 55, pp. 5393-5400 Papadopoulos, N.D. Karayiarmi, H.S. Tsakiridis, P.E. Perraki, M. Hiistoforou, E. (2010). 

Surface preparation of the dental implant prior to implantation wiH have an effect on corrosion behavior, initial metal ion release, and interface tissue response (316). The titanium and titanium aHoy dental implants in present use have many forms to assist bone ingrowth attachment including cylinders with holes, screw threaded surfaces, porous surfaces, and other types of roughened surfaces. Methods used to produce porous surfaces iaclude arc plasma... 

This method is one of the dry methods in which no chemical reaction is involved. Preparation of ultrafine particles by physical vapor deposition (PVD) dose not require washing and calcination, which are indispensable for chemical preparation such as in CP and DP methods. As waste water and waste gases are not by-produced, the arc plasma (AP) method is expected to grow in popularity as one of the industrial production methods for gold catalysts and as a clean preparation method. 

A plasma centrifugal furnace uses thermal heat transferred from arc plasma to create a molten bath that detoxifies the feed material. Organic contaminants are vaporized at temperatures of 2000 to 2500°F (1093 to 1371°C) to form innocuous products. Solids melt and are vitrified in the molten bath at 2800 to 3000°F (1540 to 1650°C). Metals are retained in this phase, which is a nonleachable, glassy residue. This method is applicable to soils contaminated with organic compounds and metals. 

Spherical particles proved to be superior in several applications owing to their favorable properties. Thus, they are used in thermal spraying for their excellent flowabil-ity, in powder metallurgy because of their excellent reproducibility in manufacturing parts with controlled porosity and as a filler material, as well. Metal microspheres can be easily produced by melt atomization. Similar method in the case of ceramics is impractical. Micron-sized ceramic particles, however, can be smelted by thermal plasmas that provide exceptional conditions for spheroidization due to its high temperature. In terms of purity and residence time of the particles in the hot temperature core, RF plasmas provide better conditions as compared to arc plasmas. 

An Ar stabilized direct current (DC) arc plasma at atmospheric pressure was employed to determine Cu, Fe, and Mn in wine [81]. The experimental conditions were optimized by studying the lateral distribution of the spectral line intensities of the elements assessed in aqueous and ethanolic-aqueous solutions. The method was applied to quantify Cu, Fe, and Mn in six wines from three Serbian grape-growing regions and the accuracy was checked by FA AS. 

Metallofullerenes can be synthesized typically in two ways similar to the s)mthesis of empty fullerenes, which involves the generation of a carbon-rich vapor or plasma in He or Ar gas atmosphere. The two methods have been routinely used to date for preparing macroscopic amounts of metallofullerenes the high-temperature laser vaporization or "laser-furnace method (Chai et al., 1991 Haufler et al., 1991 Ying et al., 1994) and the standard direct current (DC) arc discharge method (Haufler et al., 1990). Both methods simultaneously generate a mixture of hollow fullerenes (Ceo, C70, C76, C78, Cs4,...) together with metallofullerenes. The production of metallofullerenes can be followed by procedures to extract from soot and to separate/purify the metallofullerenes from the hollow fullerenes (see Sections 2.2, 3.1, and 3.2). 

Vacuum arc plasma discharges are intense sources of dense metal plasma, and can be used to deposit metal alloy thin films of various kind including both conventional alloys as well as non—equilibrium alloys. In our approach, the basic plasma deposition process is combined with the ion bombardment the method is environmentally friendly, highly efficient, can be scaled up to large size, and can synthesize films of a wide range of materials[5—9], A metal plasma of the required species is formed by a vacuum arc plasma gun and directed towards the substrate with a moderate streaming energy, typically in order of 100 eV. At the same time, the substrate is... 

U suaUy electrodes with a diameter of less than 6 mm are used for the arc method because the output of fullerene decreases on larger dimensions. This effect is caused by the fuUerene s sensitivity toward radiation while traveling toward cooler parts of the apparatus, the fullerene molecules are exposed to very intensive UV-rays emitted by the arc plasma. They get excited, and the resulting triplet state with a lifetime in the range of gs gives rise to an increased reactivity toward other carbon clusters C . The latter can be explained with the open-shell structure of the excited fullerene. 

A modification of the arc discharge method is reahzed in the so-called DC-arc jet (plasma jet). In this case, the electrodes are arranged in a way to form a sort of nozzle for the reactant gases. The cathode encloses the anode in a certain distance, and the gas mixture is led through the resultant gap. It partly decomposes between the electrodes before it hits the cooled substrate where the diamond film is deposited then (Figure 6.16). In this manner, an accurate control of the deposition zone is achieved, yet the results are highly dependent on the nozzle geometry and on a very constant reactant flow. 

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