Gas and liquid phase interactions at the chromium oxide cathode of a direct current arc discharge

1983 ◽  
Vol 61 (12) ◽  
pp. 1633-1642 ◽  
Author(s):  
Hubert Lange ◽  
Paul Meubus
Keyword(s):  
Chromium Oxide ◽  
Arc Discharge ◽  
Mass Transfer Rate ◽  
Bath Temperature ◽  
Liquid Oxide ◽  
Thermodynamic Conditions ◽  
Arc Current ◽  
Oxide Decomposition ◽  
Oxide Vapor ◽  
Oxide Evaporation

The behaviour of a chromium oxide liquid sample has been studied in the presence of an argon arc discharge, the oxide being contained in a cathode crucible. The arc current was maintained at 24 and 44 A, at 21 V. The arc temperature distribution range was between 7 000 and 8 500 K, while the liquid oxide temperature stabilized at 2 420 or 2 620 K, depending on the arc current used. The reduced metal was obtained in the molten bath as a mixture with its oxide and was identified by X-ray diffraction.Using the Cr(I) 434.4-nm and Cr(I) 396.3-nm, as well as the Cr(II) 321.7-nm spectral data, it could be shown that a considerable part of the reduced chromium found at the cathode may originate from the arc discharge, migration of the Cr(II) species occurring under the effect of the electric field. The thermodynamic conditions in the cathode bath cannot explain the formation of Cr from the oxide decomposition in the bath. Also, in view of the low chromium oxide vapor pressure at the prevailing bath temperature, the mass transfer rate from the cathode bath to the arc should be increased by liquid oxide projection into the arc gas, under the effect of arc impact on the cathode. This should be followed by oxide evaporation and decomposition at high temperatures. This study confirms that the arc–cathode interaction may substantially increase the amount of oxide reduction at the cathode.

scholarly journals Computer Simulation of Microsegregation of Sulphur and Manganese and Formation of MnS Inclusions while Casting Rail Steel

2016 ◽  
Vol 61 (4) ◽  
pp. 1939-1944 ◽  
Author(s):  
D. Kalisz ◽  
S. Gerasin ◽  
P. Bobrowski ◽  
P.L. Żak ◽  
T. Skowronek
Keyword(s):  
Nonmetallic Inclusions ◽  
Rail Steel ◽  
Manganese Sulfide ◽  
Final Conclusion ◽  
Steel Component ◽  
Inclusion Formation ◽  
Liquid Oxide ◽  
Thermodynamic Conditions ◽  
Chemical Composition Of Steel

Abstract The quality of rail steel is conditioned by its high mechanic qualities, which greatly depend on the presence of undesired nonmetallic inclusions. The paper is devoted to the segregation of components, mainly sulphur, and the formation of manganese sulphide in the process of steel solidification, at the casting rate of 100 and 500 K/min. Sulphur is a steel component which disadvantageously influences its numerous parameters. The oxide-sulphide and sulphide precipitations cause cracks and lower the strength of the material. This phenomenon was modeled with the use of author’s computer program based on Matsumiya interdendritic microsegregation model. The main assumptions of this model and thermodynamic conditions of inclusion formation during casting of steel are discussed in this paper. Two cases were analyzed: in the first one the MnS was assumed to form a pure and constant compound, whereas in the other one the manganese sulfide was precipitated as a component of a liquid oxide solution, and its activity was lower than unity. The final conclusion is that chemical composition of steel is the major parameter deciding about the formation of MnS inclusions.

Structure and morphology of copper oxide composite materials synthesized by the arc discharge method

2018 ◽  
Vol 32 (34n36) ◽  
pp. 1840067 ◽  
Author(s):  
F. Fang ◽  
J. Rogers ◽  
P. P. Murmu ◽  
J. Kennedy
Keyword(s):  
Composite Materials ◽  
Copper Oxide ◽  
Arc Discharge ◽  
Ion Beam ◽  
Ion Beam Analysis ◽  
X Ray ◽  
Oxide Composite ◽  
Beam Analysis ◽  
Arc Current ◽  
Discharge Method

Copper oxide is a semiconducting compound with a narrow band gap and is used for photoconductive and photothermal applications. Most of the synthesis methods for the preparation of copper oxide composite materials either are unsuitable for mass fabrication or inevitably introduce unwanted impurities. In this work, we report on the synthesis of copper oxide composite materials by the arc discharge method with a pure copper rod as the anode and graphite as the cathode. Ion beam analysis techniques, particle-induced X-ray emission and Rutherford backscattering spectrometry were used to probe the impurities in the copper oxide composites. Ion beam analysis results revealed copper and oxygen as constituent elements with no impurities. X-ray diffraction results discovered the presence of CuO, Cu2O and Cu phases in the composite materials. The morphology of the as-synthesized copper oxide was studied by scanning electron microscopy. Results clearly demonstrated that spherical particles were obtained with an average diameter of 14 [Formula: see text]m (range 2–85 [Formula: see text]m), 35 [Formula: see text]m (range 20–100 [Formula: see text]m) and 50 [Formula: see text]m (range 30–120 [Formula: see text]m) for the arc current of 60 A, 80 A and 95 A, respectively. It was found that the morphology can be controlled by the arc discharge parameters, e.g. a lower arc discharge current contributed to a smaller particle size. This is because the electric arc current influences the nucleation and the growth of the spherical structures. Due to its simplicity of synthesis, the proposed arc discharge is a promising technique for the fabrication of copper oxide composite materials for optical and electrical applications.

Synthesis of Carbon Nanostructures and CaCO3 Nanoparticles by Arc Discharge in Mineral Water

2011 ◽  
Vol 15 ◽  
pp. 57-67 ◽  
Author(s):  
V. Eskizeybek ◽  
E.S. Karabulut ◽  
A. Avci
Keyword(s):  
Electron Microscopy ◽  
Production Rate ◽  
Carbon Nanostructures ◽  
Mineral Water ◽  
Arc Discharge ◽  
Thermo Gravimetric Analysis ◽  
Gravimetric Analysis ◽  
Caco3 Nanoparticles ◽  
Multi Walled Carbon Nanotubes ◽  
Arc Current

The synthesis of multi-walled carbon nanotubes MWCNTs, carbon nanoshells, carbon nanoonions (CNOs), different types of carbon nanostructures and CaCO3 nanoparticles were performed using an arc-discharge method in mineral water. The structures of the synthesized nanostructures were visualized by scanning electron microscopy and transmission electron microscopy (TEM). Furthermore, ultraviolet-visible spectroscopy and thermo-gravimetric analysis (TGA) were used to determine the optical and thermal properties of the synthesized nanostructures. The TEM observations revealed that as-synthesized MWCNTs and CNOs have nominal diameters in the range of 10-20 nm and 30-50 nm, respectively. The CaCO3 nanoparticles were directly synthesized using arc discharge due to the presence of Ca minerals in the mineral water. The production rate of synthesized MWCNTs decreased when the arc current increased above 50 A, and the production rate of different nanoparticles increased with increasing arc current. The thermal-oxidative stability of the carbon nanostructures using TGA was explored separately under argon and oxygen atmospheres.

scholarly journals Multiwalled Carbon Nanotube Synthesis Using Arc Discharge with Hydrocarbon as Feedstock

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
K. T. Chaudhary ◽  
Z. H. Rizvi ◽  
K. A. Bhatti ◽  
J. Ali ◽  
P. P. Yupapin
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotube ◽  
Arc Discharge ◽  
Ambient Pressure ◽  
Multiwalled Carbon Nanotube ◽  
Physical Parameters ◽  
Discharge Process ◽  
Multiwalled Carbon ◽  
Experimental Conditions ◽  
Arc Current

Synthesis of multiwalled carbon nanotube (MWCNT) by arc discharge process is investigated with methane (CH4) as background and feedstock gas. The arc discharge is carried out between two graphite electrodes for ambient pressures 100, 300, and 500 torr and arc currents 50, 70, and 90 A. Plasma kinetics such as the density and temperature for arc discharge carbon plasma is determined to find out the contribution of physical parameters as arc current and ambient pressure on the plasma dynamics and growth of MWCNT. With increase in applied arc current and ambient pressure, an increase in plasma temperature and density is observed. The synthesized samples of MWCNT at different experimental conditions are characterized by transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. A decrease in the diameter and improvement in structure quality and growth of MWCNT are observed with increase in CH4ambient pressure and arc current. For CH4ambient pressure 500 torr and arc current 90 A, the well-aligned and straight MWCNT along with graphene stakes are detected.

scholarly journals PROCESSES OF FORMATION OF NANODISPERSE ALO POWDERS WITH CARBON IN A DC ELECTRIC ARC

2020 ◽  
pp. 758-764
Author(s):  
Наталья Анатольевна Алексеенко ◽  
Максим Николаевич Коваленко ◽  
Людмила Владимировна Маркова ◽  
Анатолий Павлович Зажогин
Keyword(s):  
Aluminum Alloy ◽  
Carbon Material ◽  
Arc Discharge ◽  
Electric Arc ◽  
Alloy Electrode ◽  
Carbon Electrode ◽  
Plasma Arc ◽  
Air Atmosphere ◽  
Order Of Magnitude ◽  
Arc Current

Исследованы процессы образования нанодисперсных порошков AlO с углеродом в электрической дуге постоянного тока при воздействии дугового разряда между электродом из алюминиевого сплава Д16Т и угольным электродом в атмосфере воздуха. Изучено влияние силы тока дуги на плазменно-дуговой синтез алюминий-углеродного материала, прекурсора для получения полых наночастиц AlO . Установлено, что с увеличением силы тока дуги от 4 до 14 А количество продукта увеличивается почти на порядок, несмотря на конкурирующие процессы диссоциации AlO при увеличении температуры от 5000 до 5500К. The nanodisperse AlO powders formation with carbon in a DC electric arc under the influence of an arc discharge between an D16T aluminum alloy electrode and a carbon electrode in the air atmosphere are studied. The effect of the arc current on the plasma-arc synthesis of an aluminum-carbon material, a precursor for production of hollow AlO nanoparticles, was studied. It is found that with an increase in the arc current from 4 to 14 A, the amount of product increases by almost an order of magnitude, despite competing dissociation processes with an increase in temperature from 5000 to 5500 К.

PREPARATION OF PURE COBALT NANOPARTICLES BY ELECTRIC ARC DISCHARGE METHOD IN ETHYLENE GLYCOL

2013 ◽  
Vol 27 (09) ◽  
pp. 1350057 ◽  
Author(s):  
S. HOSSEYNIZADEH KHEZRI ◽  
A. YAZDANI ◽  
R. KHORDAD ◽  
B. ABEDI RAVAN
Keyword(s):  
Ethylene Glycol ◽  
Arc Discharge ◽  
Cobalt Nanoparticles ◽  
Electric Arc ◽  
Visible Spectroscopy ◽  
Pure Cobalt ◽  
Electric Arc Discharge ◽  
Arc Current ◽  
Uv Visible ◽  
Discharge Method

Synthesis of Cobalt nanoparticles often entails toxic and expensive physical-chemistry methods. Fabrication of pure cobalt nanoparticles (NPs) using a simple and low-cost electric arc discharge method in ethylene glycol (EG) is suggested for the first time. The effect of different arc discharge currents (10, 20 and 30 A) on the size and optical absorption of the NPs are studied. Dynamic light scattering (DLS) and UV-visible spectroscopy result indicate that at an arc current of 10 A NPs of about 92.95 nm are produced and increasing the arc current leads to larger NPs. UV-visible spectroscopy data shows that the solvent gets more and more transparent with time. Sonication proves that this effect is related to agglomeration of the NPs. Formation of the pure Co NPs are evidenced by means of X-ray diffraction (XRD) measurements which gives an average size of about 21 nm using Scherrer's relation. Magnetization measurements of the samples are carried out by Alternating Gradient Force Magnetometer (AGFM). The results demonstrate the ability of the arc discharge method for direct formation of Co NPs in EG medium.

scholarly journals Determination of the voltage drop on a high-current vacuum arc discharge under conditions of a limited cross-section of the plasma flow

2021 ◽  
Vol 2064 (1) ◽  
pp. 012019
Author(s):  
A G Rousskikh ◽  
A S Zhigalin ◽  
V I Oreshkin ◽  
P Artyomov
Keyword(s):  
Cross Section ◽  
Plasma Flow ◽  
Voltage Drop ◽  
Arc Discharge ◽  
Vacuum Arc ◽  
High Current ◽  
Plasma Gun ◽  
Flow Through ◽  
Arc Current

Abstract The work is devoted to the study of the high-current vacuum arc discharge characteristics under conditions of a limited cross-section of the plasma flow. The experiments were carried out on the IMRI-5 setup with a sinusoidal arc current amplitude of 300–350 kA and a rise time of 500 ns. Aluminum rods with diameters from 3 to 7 mm were used as a cathode. The plasma flow was formed in a channel whose diameter was equal to that of the cathode. The features of the formation of a plasma jet with various configurations of the used plasma gun are described. The electrophysical parameters of the arc discharge are presented. Theoretical estimates of the voltage drop across the high-current arc during the outflow of a plasma flow through holes with a limited diameter are provided.

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