scholarly journals THERMODYNAMIC MODELING OF OXIDE MELTS OF CaO - Al2O3 - SiO2 SYSTEMS

2019 ◽  
Vol 63 (1) ◽  
pp. 45-50
Author(s):  
Svetlana E. Pratskova ◽  
Vladimir A. Burmistrov ◽  
Anna A. Starikova
Keyword(s):  
Phase Diagrams ◽  
Thermodynamic Modeling ◽  
Binary Systems ◽  
Thermodynamic Description ◽  
Ternary Systems ◽  
Oxide Melt ◽  
State Diagrams ◽  
Gibbs Energies ◽  
Metallurgical Slags ◽  
Oxide Melts

Oxide melts of the CaO – Al2O3 – SiO2 system are the basis of metallurgical slags. Therefore, the thermodynamic properties of this system have been repeatedly studied experimentally, and attempts have been made to describe them theoretically. Thermodynamic modeling of the state diagrams of the CaO – Al2O3, CaO – SiO2, Al2O3 – SiO2 binary systems, as well as the CaO – Al2O3 – SiO2 ternary system was performed. In the course of the work, expressions for the thermodynamic description of the activities of the components of the oxide melt of this system are derived. For the calculation, a generalized theory of regular ionic solutions was used. The energy parameters of the theory are determined, depending on the temperature and composition of the solution, using experimental data on the heat and melting point of oxides of calcium, aluminum and silicon. According to the results of the simulation, the coordinates of the points of nonvariant transformations in the phase diagrams of the binary and ternary systems under study are determined. The obtained results on thermodynamic modeling of the coordinates of the liquidus lines of the phase diagrams of the CaO – Al2O3, CaO – SiO2, Al2O3 – SiO2 binary systems were compared with the literature data for the studied systems. The calculated diagrams are in good agreement with the experimental ones, which indicates the applicability of the chosen system for the description of such oxide melts. The modeling technique used in this work allowed to estimate the Gibbs energies of formation of silicates and calcium aluminum silicates to be 3Al2O3∙2SiO2, 3CaO∙SiO2, 2CaO∙SiO2, 3CaO∙2SiO2, CaO∙SiO2, CaO∙Al2O3∙2SiO2, 2CaO∙Al2O3∙SiO2 on the base of obtained aquations for of activities of the components and calculated parameters of the theory. The calculated diagrams will allow to determine the nature of the interaction between the components of the system, the conditions of formation, the composition and properties of the compounds formed, without isolating them from the system.

Calculation of phase diagrams and thermodynamic properties of 14 additive and reciprocal ternary systems containing Li2CO3, Na2CO3, K2CO3, Li2SO4, Na2SO4, K2SO4, LiOH, NaOH, and KOH

1984 ◽  
Vol 62 (3) ◽  
pp. 457-474 ◽  
Author(s):  
A. D. Pelton ◽  
C. W. Bale ◽  
P. L. Lin
Keyword(s):  
Phase Diagram ◽  
Thermodynamic Properties ◽  
Molten Salt ◽  
Phase Diagrams ◽  
Binary Systems ◽  
Ternary Phase ◽  
Ternary Phase Diagram ◽  
Ternary Systems ◽  
Maximum Error ◽  
Critical Assessment

Phase diagrams and thermodynamic properties of five additive molten salt ternary systems and nine reciprocal molten salt ternary systems containing the ions Li+, Na+, [Formula: see text], OH− are calculated from the thermodynamic properties of their binary subsystems which were obtained previously by a critical assessment of the thermodynamic data and the phase diagrams in these binary systems. Thermodynamic properties of ternary liquid phases are estimated from the binary properties by means of the Conformal Ionic Solution Theory. The ternary phase diagrams are then calculated from these thermodynamic properties by means of computer programs designed for the purpose. It is found that a ternary phase diagram can generally be calculated in this way with a maximum error about twice that of the maximum error in the binary phase diagrams upon which the calculations are based. If, in addition, some reliable ternary phase diagram measurements are available, these can be used to obtain small ternary correction terms. In this way, ternary phase diagram measurements can be smoothed and the isotherms drawn in a thermodynamically correct way. The thermodynamic approach permits experimental data to be critically assessed in the light of thermodynamic principles and accepted solution models. A critical assessment of error limits on all the calculated ternary diagrams is made, and suggestions as to which composition regions merit further experimental study are given.

scholarly journals Thermodynamic modeling of phase equilibria in the system Na2O – CaO – Al2O3

2019 ◽  
Vol 57 (2) ◽  
pp. 111-115
Author(s):  
Svetlana E. Pratskova ◽  
◽  
Evgenia S. Nechaeva ◽  
Keyword(s):  
Phase Equilibria ◽  
Optical Fibers ◽  
Thermodynamic Modeling ◽  
Binary Systems ◽  
Liquid Solution ◽  
Exothermic Effect ◽  
Regression Equations ◽  
Melt Mixing ◽  
Energy Parameters ◽  
State Diagrams

The thermodynamic properties of melts of the Na2O – CaO – Al2O3 system are of considerable interest for metallurgy, technology of ceramic materials, optical fibers. State diagrams CaO – Al2O3, Na2O – Al2O3 have been studied by many researchers and do not have the generally accepted version, and the system Na2O – CaO has not been specifically studied. In the work, thermodynamic modeling of the phase equilibria of the Na2O – CaO – Al2O3 system was carried out within the framework of the generalized theory of “regular” ionic solutions. Equations for the activities of the system components are derived. The energy parameters of the model are determined taking into account melting characteristics and experimental data. The state diagrams of binary systems are constructed using the calculated values of the Gibbs energies for the formation of sodium and calcium aluminates from the corresponding oxides. Using the regression equations of the temperature dependences of the energy parameters of binary melts of the Na2O – CaO – Al2O3 system, the molar mixing functions of the liquid solution раствора G_m^M, H_m^M, S_m^M and the excess thermodynamic functions G^E, H^E, S^E were calculated at 1500-1800 oC. Lime-alumina melts are stable at all temperatures, experiencing negative deviations from ideality. The Gibbs excess energy G^E is negative and in absolute value varies from 5 to 90 kJ/mol. With an increase in the concentration of Al2O3 in the melt and temperature, a tendency toward disorder is clearly manifested: the entropy of the melt mixing changes its sign from “minus” to “plus”. Na2O – Al2O3 melts are formed with an exothermic effect and ordering, and are also stable. They experience strong negative deviations (for G^E) from ideality. However, the situation changes at 55 mol. % Al2O3 and 1700-1800 oС melts of the system are unstable.

Thermodynamic Modeling of Phase Equilibria in the FeO-MgO-Al2O3 System

2020 ◽  
Vol 989 ◽  
pp. 3-9 ◽  
Author(s):  
O.V. Samoilova ◽  
L.A. Makrovets
Keyword(s):  
Experimental Data ◽  
Phase Equilibria ◽  
Phase Diagrams ◽  
Thermodynamic Modeling ◽  
Thermodynamic Stability ◽  
Thermodynamic Model ◽  
Liquidus Surface ◽  
Melt Temperature ◽  
Oxide Melt ◽  
Solid Phases

Thermodynamic modeling of coordinates of phase diagrams’ liquidus lines of the FeO–MgO, FeO–Al2O3, MgO–Al2O3 systems and coordinates of phase diagram’s liquidus surface of the FeO–MgO–Al2O3 system has been carried out. In the course of work, a thermodynamic model which describes activity of oxide melt had been selected for each of the systems; energy parameters of the model have been determined. Regions of thermodynamic stability of solid phases which are at equilibrium with the oxide melt have been determined. Results of the modeling have been compared with experimental data existing in the literature. Modeling technique has also allowed evaluating enthalpies and entropies of FeAl2O4 and MgAl2O4 compounds’ formation out of components of the oxide melt. The obtained results are of interest for steelmaking industry processes when determining the melt temperature of a slag containing oxides of iron, magnesium and aluminum.

Thermodynamic Calculation of Bi-Au-Lu, Nd Ternary Systems

2016 ◽  
Vol 850 ◽  
pp. 444-451
Author(s):  
Shu Liang Wang ◽  
Lu Jiang Zhou ◽  
Jia Lian Li ◽  
Xiao Hong Wang ◽  
Yuan Hua Lin ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Intermetallic Compounds ◽  
Binary Systems ◽  
Ternary Systems ◽  
Free Energies ◽  
Gibbs Energies ◽  
Solution Models ◽  
New Type ◽  
Free Solder ◽  
Kister Equation

With available melting point and hardness, the Bi-based filler alloy is considered as one choice of high-temperature Pb-free solder. Phase diagram can play an important role in the design of new type of Pb-free solder.In the present work, the thermodynamic assessments of the Au-Nd and the Au-Lu binary systems have been carried out by the Calculation of Phase Diagram (CALPHAD) method based on the available experimental data. The Gibbs free energies of the solution phases were described by subregular solution models with the Redlich-Kister equation, and those of the intermetallic compounds were described by sublattice models. A set of self-consistent and reasonable thermodynamic parameters is obtained for the binary systems, which describes the Gibbs energies of the solution phases and the intermetallic compounds phases. Additionally, combined the reported Bi-Au, Bi-Lu and Bi-Nd binary systems, the thermodynamic database of the Bi-Au-Lu and the Bi-Au-Nd ternary systems have been developed, which will provide important thermodynamic information for the phase equilibria of the multicomponent Bi-based alloy systems.

Thermodynamic Study of Ag-Au-Gd, Tb Ternary Systems

2015 ◽  
Vol 814 ◽  
pp. 313-318 ◽  
Author(s):  
Jia Lian Li ◽  
Shu Liang Wang ◽  
Lu Jiang Zhou ◽  
Xiao Hong Wang ◽  
Yuan Hua Lin ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Phase Diagrams ◽  
Binary Systems ◽  
Lattice Models ◽  
Ternary Systems ◽  
Calculated Phase Diagram ◽  
Thermodynamic Database ◽  
Filler Alloy ◽  
Free Energies ◽  
Significant Information

The addition of the rare earth elements into the Ag-based filler alloy, which is typical and important, can control and eliminate the negative effect of impurity elements, and furthermore, it improves the spreading property of the Ag-based filler alloy. Phase diagram provides an important direction for materials design of the Ag-based filler alloy. Thus it is necessary to investigate the phase diagrams and construct the thermodynamic database. On the basis of this background, thermodynamic assessments of the Au-Gd, Tb binary systems were carried out by using the CALPHAD (Calculation of Phase Diagrams) method based on the experimental data including thermodynamic properties and phase equilibrium. The Gibbs free energies of the solution phases were described by sub-regular solution models with the Redlich-Kister equation, while all of the intermetallic compounds were described by sub-lattice models. A consistent set of thermodynamic parameters was derived from describing the Gibbs free energies of each solution phase and intermetallic compound. The calculated phase diagram achieved consistency with the available experiments. Then combined with the assessed relevant binary systems, the Ag-Au-Gd, Tb ternary systems have been predicted. The thermodynamic database of these ternary systems has been developed to present the significant information for the design of Ag-based filler alloys.

scholarly journals Thermodynamic calculations in alloys Ti-Al, Ti-Fe, Al-Fe and Ti-Al-Fe

2008 ◽  
Vol 44 (1) ◽  
pp. 49-61 ◽  
Author(s):  
Ana Kostov ◽  
B. Friedrich ◽  
D. Zivkovic
Keyword(s):  
Phase Diagrams ◽  
Ternary Alloy ◽  
Ternary Systems ◽  
Thermodynamic Calculations ◽  
Calculated Phase ◽  
Gibbs Energies ◽  
Different Temperatures ◽  
Binary And Ternary Systems ◽  
Thermodynamic Determination

Thermodynamic calculations of three binary Ti-based alloys: Ti-Al, Ti-Fe, and Al-Fe, as well as ternary alloy Ti-Al-Fe, is shown in this paper. Thermodynamic calculations involved thermodynamic determination of activities, coefficient of activities, partial and integral values for enthalpies and Gibbs energies of mixing and excess energies at different temperatures: 1873K, 2000K and 2073K, as well as calculated phase diagrams for the investigated binary and ternary systems. The FactSage is used for all thermodynamic calculations.

scholarly journals Thermodynamic Modeling of Hydrogen Storage Capacity in Mg-Na Alloys

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
S. Abdessameud ◽  
M. Mezbahul-Islam ◽  
M. Medraj
Keyword(s):  
Hydrogen Storage ◽  
Thermodynamic Modeling ◽  
Binary Systems ◽  
Equilibrium Diagram ◽  
Thermodynamic Description ◽  
System A ◽  
Different Temperatures ◽  
Catalytic Role ◽  
Temperature Equilibrium ◽  
First Time

Thermodynamic modeling of the H-Mg-Na system is performed for the first time in this work in order to understand the phase relationships in this system. A new thermodynamic description of the stable NaMgH3hydride is performed and the thermodynamic models for the H-Mg, Mg-Na, and H-Na systems are reassessed using the modified quasichemical model for the liquid phase. The thermodynamic properties of the ternary system are estimated from the models of the binary systems and the ternary compound using CALPHAD technique. The constructed database is successfully used to reproduce the pressure-composition isotherms for MgH2 + 10 wt.% NaH mixtures. Also, the pressure-temperature equilibrium diagram and reaction paths for the same composition are predicted at different temperatures and pressures. Even though it is proved that H-Mg-Na does not meet the DOE hydrogen storage requirements for onboard applications, the best working temperatures and pressures to benefit from its full catalytic role are given. Also, the present database can be used for thermodynamic assessments of higher order systems.

Derivation of complete phase diagrams for ternary systems with immiscibility phenomena and solid–fluid equilibria

2002 ◽  
Vol 74 (10) ◽  
pp. 1871-1884 ◽  
Author(s):  
V. M. Valyashko
Keyword(s):  
Phase Diagrams ◽  
Binary Systems ◽  
Volatile Component ◽  
Fluid Phase ◽  
Ternary Systems ◽  
Systematic Classification ◽  
Binary Fluid ◽  
Binary Phase Diagrams ◽  
Starting Point

Four main types of binary fluid-phase diagrams and available experimental data on binary systems are used as a starting point for derivation of the systematic classification of binary complete phase diagrams by the method of continuous topological transformations. This method and the classification of binary phase diagrams, containing the boundary versions of phase diagrams with ternary nonvariant points, are applied to derive the main types of fluid and complete phase diagrams for ternary systems with one volatile component and immiscibility phenomena in two constituent binary subsystems. The results gained from this analysis of derived fluid and complete phase diagrams of ternary systems are represented.

scholarly journals Thermodynamic predicting of Si-Me (Me = Ti, Al) binary systems

2007 ◽  
Vol 43 (1) ◽  
pp. 29-38 ◽  
Author(s):  
A. Kostov ◽  
D. Zivkovic ◽  
B. Friedrich
Keyword(s):  
Phase Diagrams ◽  
Thermodynamic Analysis ◽  
Binary Systems ◽  
Thermodynamic Calculations ◽  
Gibbs Energies ◽  
Different Temperatures ◽  
Thermodynamic Determination

Thermodynamic predicting analysis of Si-based binary systems - Ti-Si, and Al-Si, are shown in this paper. Thermodynamic analysis involved thermodynamic determination of activities, coefficient of activities, partial and integral values for enthalpies and Gibbs energies of mixing and excess energies at different temperatures: 2000K, 2400K and 2473K, as well as calculation of phase diagrams for the investigated binaries. The FactSage was used for all thermodynamic calculations. .

scholarly journals MODELING OF QUASIBINARIES OF Na+, Сa2+ // O2-, F- SYSTEM

2018 ◽  
Vol 59 (1) ◽  
pp. 19
Author(s):  
S.E. Pratskova ◽  
A.G. Tyurin
Keyword(s):  
Gibbs Energy ◽  
Phase Equilibria ◽  
Phase Diagrams ◽  
Exchange Reaction ◽  
Thermodynamic Modeling ◽  
Binary Systems ◽  
Standard Gibbs Energy ◽  
Ionic Solutions ◽  
System Components ◽  
F System

Thermodynamic modeling of phase equilibria of the Na +, Ca2 + // O2-, F- system in the frame of the generalized theory of "regular" ionic solutions was carried out. The equations for the activities of the system components were derived. The standard Gibbs energy of the exchange reaction was calculated. The values of the energy parameters of the model were determined and the phase diagrams of the binary systems were constructed.

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