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.

Thermodynamic Modeling of Phase Equilibria in the FeO-Al2O3-Cr2O3 and MgO-Al2O3-Cr2O3 Systems

2020 ◽  
Vol 989 ◽  
pp. 204-209 ◽  
Author(s):  
Gennady G. Mikhailov ◽  
L.A. Makrovets ◽  
O.V. Samoilova
Keyword(s):  
Phase Equilibria ◽  
Phase Diagrams ◽  
Thermodynamic Modeling ◽  
Liquidus Surface ◽  
Complex Oxide ◽  
Thermodynamic Models ◽  
Ionic Solutions ◽  
Calculated Phase ◽  
Energy Parameters

Thermodynamic modeling of phase equilibria and further construction of a full projection of the liquidus surface in the FeO–Al2O3–Cr2O3 and MgO–Al2O3–Cr2O3 systems were carried out. Theories of sub-regular ionic solutions, regular ionic solutions and ideal ionic solutions were used for calculation. Values of energy parameters of the used thermodynamic models were obtained in the course of the research. These values might be applicable for further modeling of more complex oxide slag systems which are formed in the process of manufacture of chromic steels. Calculated phase diagrams for the FeO–Al2O3–Cr2O3 and MgO–Al2O3–Cr2O3 systems were compared with available data from literature sources.

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.

Evaluation of the Thermodynamic Properties and Phase Equilibria of the Ordered γ’ and Disordered γ Phases in the Ni-Al-Ta System

2002 ◽  
Vol 755 ◽  
Author(s):  
Shihuai Zhou ◽  
Long-Qing Chen ◽  
Rebecca A. MacKay ◽  
Zi-Kui Li u
Keyword(s):  
Experimental Data ◽  
Thermodynamic Properties ◽  
Gibbs Energy ◽  
Phase Equilibria ◽  
Phase Diagrams ◽  
Gibbs Energy Function ◽  
Ternary Interaction ◽  
Two Phases ◽  
Rich Side ◽  
Good Agreement

ABSTRACTThe phase equilibria and thermodynamic properties of the ternary Ni-Al-Ta system on Ni-rich side were analyzed. Thermodynamic descriptions of the liquid, γ-fcc, γ'-L12, and π-Ni6AlTa phases were obtained using the CALPHAD (CALculation of PHase Diagrams) technique. The thermodynamics of γ-fcc and γ'-L12 phases were modeled with a single Gibbs energy function taking into account the crystallographic relation between the two phases. The ternary interaction parameters of the liquid and fcc phases were also determined. The calculated phase diagrams of the ternary Ni-Al-Ta system show a good agreement with experimental data.

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.

scholarly journals Phase Equilibria for Carbon Capture and Storage

2020 ◽  
Author(s):  
Catinca Secuianu ◽  
Sergiu Sima
Keyword(s):  
Carbon Dioxide ◽  
Phase Equilibria ◽  
Phase Behavior ◽  
Phase Diagrams ◽  
Carbon Capture ◽  
Binary Systems ◽  
High Pressures ◽  
Carbon Capture And Storage ◽  
Organic Substances ◽  
And Storage

Carbon dioxide (CO2) is an important material in many industries but is also representing more than 80% of greenhouse gases (GHGs). Anthropogenic carbon dioxide accumulates in the atmosphere through burning fossil fuels (coal, oil, and natural gas) in power plants and energy production facilities, and solid waste, trees, and other biological materials. It is also the result of certain chemical reactions in different industry (e.g., cement and steel industries). Carbon capture and storage (CCS), among other options, is an essential technology for the cost-effective mitigation of anthropogenic CO2 emissions and could contribute approximately 20% to CO2 emission reductions by 2050, as recommended by International Energy Agency (IEA). Although CCS has enormous potential in numerous industries and petroleum refineries due their large CO2 emissions, a significant impediment to its utilization on a large scale remains both operating and capital costs. It is possible to reduce the costs of CCS for the cases where industrial processes generate pure or rich CO2 gas streams, but they are still an obstacle to its implementation. Therefore, significant interest was dedicated to the development of improved sorbents with increased CO2 capacity and/or reduced heat of regeneration. However, recent results show that phase equilibria, transport properties (e.g., viscosity, diffusion coefficients, etc.) and other thermophysical properties (e.g., heat capacity, density, etc.) could have a significant effect on the price of the carbon. In this context, we focused our research on the phase behavior of physical solvents for carbon dioxide capture. We studied the phase behavior of carbon dioxide and different classes of organic substances, to illustrate the functional group effect on the solvent ability to dissolve CO2. In this chapter, we explain the role of phase equilibria in carbon capture and storage. We describe an experimental setup to measure phase equilibria at high-pressures and working procedures for both phase equilibria and critical points. As experiments are usually expensive and very time consuming, we present briefly basic modeling of phase behavior using cubic equations of state. Phase diagrams for binary systems at high-pressures and their construction are explained. Several examples of phase behavior of carbon dioxide + different classes of organic substances binary systems at high-pressures with potential role in CCS are shown. Predictions of the global phase diagrams with different models are compared with experimental literature data.

scholarly journals Phase complex model of ternary reciprocal system Na+,Sr2+||WO42-,MoO42-

2019 ◽  
Vol 59 (8) ◽  
pp. 103-115
Author(s):  
Alexander V. Burchakov ◽  
Keyword(s):  
Phase Equilibria ◽  
Solid Solutions ◽  
Binary Systems ◽  
Reciprocal System ◽  
Condensed State ◽  
Continuous Series ◽  
Algebraic Equations ◽  
Reaction Products ◽  
System Components ◽  
Phase Complex

The paper presents the results of a theoretical study of the phase complex of a three-component reciprocal system consisting of sodium and strontium tungstates and molybdates. Previously, a literature review was conducted on data on phase equilibria in the condensed state of individual salts, binary faceting systems. In two Na2MoO4 – SrMoO4 and Na2WO4 – SrWO4 binary systems, a eutetic equilibrium is observed with the formation of solid phases corresponding to the system components, and in two other Na2MoO4 – Na2WO4 and SrMoO4 – SrWO4 binary systems, one phase of a continuous series of solid solutions crystallizes. Based on the mathematical model of the molar balance, one can uniquely determine the quantities of reaction products, the molecular formulas of solid solutions, and the equations of chemical reactions for an arbitrary mixture of system components. This model represents a set of algebraic equations by which the balance is calculated. To build a 3D computer model, the paper presents the equations for the conversion of coordinates from barycentric to Cartesian. The model is implemented in concentration-temperature coordinates using the KOMPAS-3D program using experimental data on the system. The model is built in two interpretations: based on data on the faceting elements and on the basis of all available data about the system. Comparison of the two models makes it possible to evaluate the predictive ability carried out using 3D modeling. From this comparison, it was found that using the 3D model it is possible to conduct a preliminary a priori forecast of phase equilibria in order to identify the structure of phase diagrams at the qualitative and quantitative levels. The projection of the crystallization polytherm onto the square of the compositions is represented by two fields of solid solutions – Na2MoxW1-xO4 and SrMoxW1-xO4. Isothermal and polythermal sections were constructed. The system implements di- and monovariant equilibria.

scholarly journals Modeling of phase equilibria of the system Ca, Fe // O, S in the framework of the generalized theory of regular ionic solutions

2019 ◽  
Vol 58 (5) ◽  
pp. 127-132
Author(s):  
Svetlana E. Pratskova ◽  
◽  
Alexey O. Mardanov ◽  
Keyword(s):  
Experimental Data ◽  
Cast Iron ◽  
Gibbs Energy ◽  
Exchange Reaction ◽  
Molar Fraction ◽  
Ionic Solutions ◽  
Energy Parameters ◽  
State Diagrams ◽  
Binary State ◽  
Melting Characteristics

Sulfur refers to the harmful impurities of cast iron, deteriorating the quality of the metal. Therefore, much attention is paid to the problem of reducing sulfur in the iron, and then in steel. Most of the sulfur is dissolved in the iron as FeS. One method of non-domain removal of sulfur from cast iron is desulfurization. As a reagent in this process, powdered calcined lime CaO is used. The article presents the results of thermodynamic modeling of the Ca, Fe // O, S system within the framework of the generalized theory of "regular" ionic solutions. The equations for calculating the activity of the components of the system under study are derived. The energy parameters of the model are calculated taking into account the experimental data and melting characteristics of pure oxides and sulfides for the systems CaO – CaS, FeO – FeS, FeS – CaS, FeO – CaO. The values of the energy parameters are in good agreement with the experimental data. Calculated binary state diagrams of the system under study. The diagrams FeO – FeS, СaO – CaS, FeO – CaO, FeS – CaS are calculated over the entire molar fraction from 0 to 1. The Gibbs energy of the exchange reaction FeS + CaO = FeO + CaS is determined on the basis of the following data: thermodynamic parameters characterizing the processes the melting of oxides and sulfides of iron and calcium, the values of the reduced thermodynamic potential Ф_T^o and standard enthalpies of substances ∆_f H_(0,i)^o at absolute zero. Based on the values of the energy parameters calculated for the doubles and the Gibbs energy of the exchange reaction, a FeS – CaO diagram with a simple eutectic at 90 mol. % FeS and 10 mol. % CaO, melting at 1407 K.

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.

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