Begell House Inc.
High Temperature Material Processes: An International Quarterly of High-Technology Plasma Processes
HTM
1093-3611
3
1
1999
MODELLING OF INDUSTRIAL AC-ARCS
1-15
10.1615/HighTempMatProc.v3.i1.10
G. A.
Saevarsdottir
Department of Materials Technology and Electrochemistry, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
Hilde Loken
Larsen
Department of Metallurgy, Norwegian University of Science and Technology (NTNU) Trondheim, Norway
Jon Arne
Bakken
NTNU, SINTEF Metallurgi Alfred Getz vei 2B N67034 ; and Department of Materials Technology and Electrochemistry, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
Electric Arc Furnace
3-phase
AC-arcs
plasma
simulation
An improved Channel Arc Model for simulation of AC arcs on ordinary PC's is presented. In this model the arc is treated as a cylindrical current conductor with uniform radius and a prescribed radial temperature distribution. In order to verify the model, laboratory arcs with I mrs ≈ 1000 A, as well as industrial arcs with I mrs ≈ 100 kA, are simulated and compared to measured values. Assuming symmetrical furnace conditions, the three-phase electric circuit is first simplified to a one-phase description which is compared to values from an industrial submerged arc furnace. In order to generalize the model, and to be able to simulate also asymmetrical furnace conditions, the complete three-phase circuit is included and results obtained from the three-phase simulations are compared with one-phase simulations. In addition, the effect of a charge current, which bypasses the arc, is shown in the three-phase description.
SOME ASPECTS OF ALLOYING AND REFINING OF HIGH NITROGEN STEELS IN A PLASMA FURNACE UNDER ELEVATED PRESSURE
17-24
10.1615/HighTempMatProc.v3.i1.20
Wlodzimierz
Derda
Metallurgy and Engineering Metrials Technical University of Czestochowa, Poland
Jerzy
Siwka
Faculty of Metallurgy and Materials Engineering, Technical University of Czestochowa Al. Armii Krajowej 19, 42-200 Czestochowa, Poland
Jan
Jowsa
Faculty of Metallurgy and Engineering Metrials Technical University of Czestochowa, Poland
High Cr-steels
calcium refining agent
nitriding.
Experimental results of refining and nitriding of High Nitrogen Steels in an air-tight plasma furnace are presented. The one-stage Pressure Plasma Melting Process (PPMP) was realized under elevated pressure up to 0.5 MP a for a high Cr and Mn steel. Metallic calcium or CaF2-Ca alloy were used as the refining agent. The steel ingots cast under elevated pressure were hot forged to receive round bars and after their solutioning the samples were prepared to determine their mechanical properties.
RADIATION EMISSION OF THERMAL PLASMA IN 02, H20, C02 AND AIR
25-37
10.1615/HighTempMatProc.v3.i1.30
H.
Riad
Departement d'Enseignements Generaux et Techniques, Ecole Mohammadia d'ingenieurs, Universite Mohamed V, Rabat-Agdal, Maroc
A.
Cheddadi
Faculté des Sciences et Techniques de Settat, B.P. 577, Settat, Maroc
Y.
Neghizadeh-Kashani
Universite Paul Sabatier, 118 route de Narbonne, F31062 Toulouse cedex 4, France
Alain
Gleizes
Centre de Physique des Plasmas et de leurs Applications de Toulouse (CPAT) UMR n° 5002 − Université Paul Sabatier, 118 Route de Narbonne F31062 Toulouse Cedex 4 - France
We present the calculation of net radiation emitted by the hottest regions of various thermal plasmas, in which we consider that the molecules are dissociated. This computation have been effected, in the pure oxygen, water, carbon dioxide and air thermal plasmas assuming isothermal and local thermodynamic equilibrium (LTE) medium, by solving the radiative transfer equation. The results show that the nature of the species has a great influence on the net emission coefficient. In spite of the strong absorption of the resonance lines, these lines constitute in general the main contribution to the total net emission.
ABOUT ROTATIONAL TEMPERATURE MEASUREMENTS AND THERMODYNAMIC EQUILIBRIUM IN RF GLOW DISCHARGES
39-50
10.1615/HighTempMatProc.v3.i1.40
Spyros
Stamou
Plasma Chemistry Department of Chemical Engineering, University of Patras P.O.Box 1407, 26500, Patras, Greece
Dimitris
Mataras
Plasma Technology Laboratory -Dept. of Chem. Engineering-University of Patras, P.O.Box 1407, 26500 Patra, Greece
Dimitrious E.
Rapakoulias
Plasma Technology Lab, Dept. Chem. Engineering, University of Patras, P.O.Box 1407, 26500 Patra, Greece
Rotational temperature
emission spectroscopy
silane
simulation
Boltzman
The rotational temperature of the А2Δ excited state of SiH has been determined in a silane r.f. glow-discharge by optical emission spectroscopy, using both a revised Boltzman diagram method and a detailed simulation of the emission spectrum utilising a least squares fitting (LSF) method. It is shown here that the LSF is more reliable and a careful use can lead to accurate results. This is accomplished by using an improved term value formula and an optimisation of the set of constants are used to calculate the best possible simulation of the spectrum. On the other hand, important informations about the achievement of thermodynamic equilibrium are obtained, with the use of the Boltzman plot method. It is shown that the population distribution in the rotational levels of a short-lived electronic state is well described by Boltzman statistics. In both methods, the experimentally determined FWHM of the optical system is of major importance.
MOLTEN SALT REACTOR TECHNOLOGY FOR SEPARATION AND TRANSMUTATION
51-66
10.1615/HighTempMatProc.v3.i1.50
V.V.
Ignatiev
RRC - Kurchatov Institute, Moscow, RF, 123182
K.F.
Grebenkine
RFNC-All-Russian Institute of Technical Physics, Snezhinsk, RF, 454070
S.A.
Konakov
RRC - Kurchatov Institute, Moscow, RF 123182
S.A.
Subbotine
RRC - Kurchatov Institute, Moscow, RF, 123182
R.Y.
Zakirov
RRC - Kurchatov Institute, Moscow, RF, 123182
transmutation
processing
losses to wastes
molten salt fluorides.
The most important developments regarding the available options to reduce actinide inventory will be discussed. In order to find optimal solution for achieving actinide reduction goals a possibility of creating a multicomponent nuclear power system in which alongside thermal and fast reactors, molten salt burner reactors will be presented.
The relation between necessary single cycle transmuted fraction, fuel cycle processing losses and total losses to waste will be defined. An attempt is made to arrange the possible systems on order performance with regard to their potential to reduce the actinide inventory and actinide losses to wastes.
The objective of this paper is to illustrate clearly the potential advantages of innovative molten salt fluoride based reactor technology integrated with nonaqueous processing methods, including reductive extraction, electrorefining and electrodeposition relative to traditional ones.
Also, this contribution aims to review the status of molten salt reactor technology, including Russian experience, to evaluate the importance of remaining uncertainties and to identify the additional work needed.
INTERCALATION FROM MOLTEN SALTS
67-76
10.1615/HighTempMatProc.v3.i1.60
Intercalation. Molten Salts. Graphite. Lithium titanate. Nanotubes
Intercalation is the reversible insertion of a chemical species into a host structure. Intercalation into graphite and other forms of carbon in the Hall Heroult cell is well known. This paper explores intercalation into other materials from fused salts and discusses applications of this phenomena in batteries and novel methods for the removal of impurities from molten metals. Lastly, the preparation of nanotubes by intercalation into graphite is discussed.
Thermodynamic Assessment of the NaCl-DyCl3 Molten Salt System
77-89
10.1615/HighTempMatProc.v3.i1.70
F.
Da Silva
IUSTI, CNRS-UMR 6595,Technopole de chateau-Gombert, 5 rue Enrico Fermi, 13453 Marseille cedex 13, France
sodium chloride
dysprosium chloride
thermodynamic assessment
phase diagram
substitution model
associated model.
Phase equilibrium in the NaCl-DyCl3 system were evaluated by numerical calculation with the Thermo-Calc software. Recent experimental thermodynamic data relative to pure DyCl3 (entropy of phase transitions) and to the mixture (enthalpy of mixing) complemented the phase diagram reported in literature. All compounds (Na3DyCl6, NaDyCl4, and NaDy2Cl7) were treated as stoichiometric compounds.
A simple substitution model revealed unsuitable for this system which includes ions of different valences and also non-purely ionic interactions. A more realistic description is proposed in the present work. It takes into account recent structural features obtained from neutron diffraction experiments carried out both on DyCl3 and NaCl-DyCl3 melts and also the results of Molecular Dynamics (MD) simulation. All the above results suggest that stable DyCl63− species are likely to exist in the melt. Thermodynamic modeling was made accordingly.
A better optimization of the system was obtained and yielded a consistent set of thermodynamic data. The experimental enthalpy of mixing, in particular, was represented quite satisfactorily while a poor agreement has been observed with a simple substitution model.
HIGH TEMPERATURE ELECTRODEPOSITION OF ZnSe
91-103
10.1615/HighTempMatProc.v3.i1.80
Sylvie
Sanchez
Laboratorio de Sales Fundidas, Departemento de Quimica Analitica Facultad de Ciencas de Valladolid Prado de la Magdalena s/n - 47011 Valladolid - Spain
Molten salt
Electrodeposition
ZnSe
Thin layers
Photovoltaic
ZnSe is a good candidate both for photovoltaic applications and laser technology because of its large band gap. High temperature electrodeposition was chosen to prepare thin layers of ZnSe on substrates made of a glass plate covered with tin oxyde, using the simultaneous reduction of Zn(II) and Se(IV) ions in the molten CaCl2-NaCl mixture at 550°C.
The first step of this study concerns the electrochemical behavior of the different Zn(II) and Se(IV) starting compounds involved in the process as well as SnO2. A thermodynamical diagram was established indicating the stability ranges of these species depending on potential and melt acidity.
Deposits were successfully obtained using a potentiostatic method at several potential values. Transparent, yellow, adherent and homogeneous films were prepared with a thickness equal to 3.5 micrometer. The atomic composition measured by X-Ray fluorescence analysis gives a ratio Se/Zn equal to 1.06 and the X-Ray diagrams show the peaks characteristic of the two different phases of ZnSe (hexagonal and cubic) and of CaCl2. The width of these peaks is characteristic of very good crystallinity of the electrodeposited films showing that post heat treatment is not required.
Effect of High Polarizability on Mobilities in Ionic Melts
105-116
10.1615/HighTempMatProc.v3.i1.90
High polarizability.
Ionic mobility
Molten salt
Ag+ ion
Tl+ ion
The effect of cations having high polarizability on the mobilities of coexisting cations as well as of the cations themselves has been studied for Ag+, Tl+ and Cs+ ions. We have previously found that the internal mobilities, u, of alkali ions in molten salts such as nitrates are well expressed by an empirical equation:u = [A/(Vm-V0)] exp(−E/RT), where Vm is the molar volume, and A, V0 and E. are parameters nearly independent of coexisting cations. In binary melts (M, Ag)NO3, uM except for М=Li+ becomes smaller than expressed by this equation; Ag+ ion has a tranquilizafion effect on uM. On the contrary, in (M, TI)NO3, uM becomes higher than according to the equation, which means that Tl+ has an agitation effect on uM. It is found that Cs+, having a high polarizability, also has an appreciable agitation effect
Morphology of Titanium Diboride Obtained by Electrochemical Synthesis from Molten Chloro-Fluoride Melt
117-124
10.1615/HighTempMatProc.v3.i1.100
Titanium diboride
electrochemical synthesis
morphology
deep profile analysis
diffusion profile.
Titanium diboride has been synthesised from NaCl-KCl-NaF-K2TiF6-KBF4 molten system at 700 °C on W cathode by DC and PCR techniques in the wide range of current densities. From comparison of Equilibrium Electrochemical Synthesis (EES) diagrams and linear voltammograms the conclusion was made, that first a thin layer of W2B will be formed, with further growth of TiB2. Deposits were analysed by X-ray diffractometry, SEM and GDOES. These techniques confirmed the validity of theoretical predictions. Finer structure has been obtained by the PCR technique compared to the DC technique. Titanium and boron atoms were found to diffuse deep into the tungsten substrate with a constant ratio of 1:2.
Phase Diagram Systematic Optimization of the REI2-MI (RE = Sm, Eu, Yb, M= Li, Na, K, Rb, Cs) Systems
125-140
10.1615/HighTempMatProc.v3.i1.110
The phase diagrams of the REI2-MI (RE = Sm, Eu, Yb, M = Li, Na, K, Rb, Cs) systems have been systematically optimized and calculated using CALPHAD approach. A set of thermodynamic functions has been optimized based on an interactive computer-assisted analysis. The calculated phase diagrams and optimized thermodynamical parameters are thermodynamically self-consistent