Thermodynamic Modeling of the K2O-Al2O3 and K2O-MgO-Al2O3 Systems with Emphasis on Β- and Βʹʹ-aluminas PDF Download
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Languages : en
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Author: Dong-Geun Kim
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Languages : en
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"Phase diagram and thermodynamic properties of the K2O-Na2O-CaO-MgO-Al2O3-SiO2 system are important in various applications, such as glass/glass-ceramics, biomass combustion, steelmaking, refractory, and geology/mineralogy. In the present work, a critical evaluation and optimization of the phase diagram and thermodynamic properties of this six-component system was performed to develop an accurate thermodynamic database for industrial and academic research. Sub-binary/ternary systems containing K2O were thermodynamically optimized based on the critical assessment of all experimental data available in the literature, and a consistent set of model parameters of solid and liquid phases describing their Gibbs energies was obtained. Key phase diagram experiments were performed for the K2O-SiO2, K2O-Al2O3, and K2O-MgO systems in order to provide new phase diagram information and resolve the inconsistencies between existing experimental data. Equilibration/quenching experiments and thermal analyses were performed using K2O-containing samples sealed in Pt capsules to overcome the experimental difficulties (high hygroscopicity and volatile nature of K2O) and provide reliable results. In the study of the K2O-SiO2 system, the eutectic reaction, Liquid → K4SiO4 + K2SiO3, was successfully measured at 714 ± 6 °C. In the K2O-MgO system, the peritectic reaction of Liquid + MgO → K6MgO4 was determined to occur at 858 ± 14 °C. These two invariant reactions were determined for the first time. In the K2O-Al2O3 system, the thermal stability of K [beta]ʹʹ-alumina was confirmed up to 1600 °C from the present experiments, and a large discrepancy in the literature related to the eutectic temperature of Liquid → KAlO2 + [beta]-alumina was resolved.In the optimization of this study, the Modified Quasichemical Model (MQM) and Compound Energy Formalism (CEF) were used to describe the liquid and solid solutions, respectively, based on the structure of the solutions. In particular, solid solutions were modeled considering their lattice structure, in this way, a proper configurational entropy of the solution could be treated in the thermodynamic calculations. In the study of K2O-MgO-Al2O3 system, for example, a new solid solution model was developed to describe the details of ionic substitutions in non-stoichiometric K [beta]- and [beta]ʹʹ-alumina solutions. In both K2O-MgO-SiO2 and K2O-Al2O3-SiO2 melt, associates K2MgSiO4 and KAlO2 were considered, respectively, to describe the phase diagram, thermodynamic properties and structural data of liquid phase more accurately. With the model parameters optimized in binary and ternary systems, the phase diagram and thermodynamic properties of higher order systems in the K2O-Na2O-CaO-MgO-Al2O3-SiO2 system were well predicted. The database developed in this study is compatible with the FactSage thermodynamic databases and can be used for the prediction of any unexplored thermodynamic properties and phase diagram within the six-component system. Case studies of several industrial applications were also included at the end of this study." --
Author: Elena Yazhenskikh
Publisher:
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Category :
Languages : en
Pages : 115
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Author: Olga Fabrichnaya
Publisher: Springer Science & Business Media
ISBN: 9783540140184
Category : Science
Languages : en
Pages : 236
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This book presents thermodynamic data on oxides in the system MgO-FeO-Fe2O3-Al2O3-SiO2. These data are produced by a process of assessment that involves the integration of thermochemical (calorimetric) and phase equilibrium data. The latter have been selected from a number of publications in high-pressure research conducted at pressures and temperatures in the range of 1 bar to several Giga Pascals and 300 to 2500 K respectively. A unique feature of the database is that the assessment involves not only the thermodynamic data on pure end member species, but also the data on multicomponent solutions. Since the solution description follows the format used in the popular thermodynamic computational packages such as FACTSAGE, ChemSage and Thermocalc, the database is easy to incorporate in the currently used databases in these packages. The database is highly useful to those working in the field of metallurgy (e.g. slags) and ceramics. It is essential for all those who do thermodynamic modeling of the terrestrial planetary interiors.
Author: American Ceramic Society
Publisher:
ISBN:
Category : Ceramics
Languages : en
Pages : 616
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Author: Shuns? Ishihara
Publisher: Geological Society of America
ISBN: 0813723892
Category : Science
Languages : en
Pages : 391
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Author: Ramana Reddy
Publisher: Springer
ISBN: 3319487698
Category : Technology & Engineering
Languages : en
Pages : 1373
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Book Description
This collection focuses on ferrous and non-ferrous metallurgy where ionic melts, slags, fluxes, or salts play important roles in industrial growth and economy worldwide. Technical topics included are: thermodynamic properties and phase diagrams and kinetics of slags, fluxes, and salts; physical properties of slags, fluxes, and salts; structural studies of slags; interfacial and process phenomena involving foaming, bubble formation, and drainage; slag recycling, refractory erosion/corrosion, and freeze linings; and recycling and utilization of metallurgical slags and models and their applications in process improvement and optimization. These topics are of interest to not only traditional ferrous and non-ferrous metal industrial processes but also new and upcoming technologies.
Author: Jibamitra Ganguly
Publisher: Springer Science & Business Media
ISBN: 3540773061
Category : Science
Languages : en
Pages : 513
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Book Description
Based on a university course, this book provides an exposition of a large spectrum of geological, geochemical and geophysical problems that are amenable to thermodynamic analysis. It also includes selected problems in planetary sciences, relationships between thermodynamics and microscopic properties, particle size effects, methods of approximation of thermodynamic properties of minerals, and some kinetic ramifications of entropy production. The textbook will enable graduate students and researchers alike to develop an appreciation of the fundamental principles of thermodynamics, and their wide ranging applications to natural processes and systems.
Author: Daniele Mari
Publisher: Newnes
ISBN: 0080965288
Category : Technology & Engineering
Languages : en
Pages : 1809
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Book Description
Comprehensive Hard Materials, Three Volume Set deals with the production, uses and properties of the carbides, nitrides and borides of these metals and those of titanium, as well as tools of ceramics, the superhard boron nitrides and diamond and related compounds. Articles include the technologies of powder production (including their precursor materials), milling, granulation, cold and hot compaction, sintering, hot isostatic pressing, hot-pressing, injection moulding, as well as on the coating technologies for refractory metals, hard metals and hard materials. The characterization, testing, quality assurance and applications are also covered. Comprehensive Hard Materials provides meaningful insights on materials at the leading edge of technology. It aids continued research and development of these materials and as such it is a critical information resource to academics and industry professionals facing the technological challenges of the future. Hard materials operate at the leading edge of technology, and continued research and development of such materials is critical to meet the technological challenges of the future. Users of this work can improve their knowledge of basic principles and gain a better understanding of process/structure/property relationships. With the convergence of nanotechnology, coating techniques, and functionally graded materials to the cognitive science of cemented carbides, cermets, advanced ceramics, super-hard materials and composites, it is evident that the full potential of this class of materials is far from exhausted. This work unites these important areas of research and will provide useful insights to users through its extensive cross-referencing and thematic presentation. To link academic to industrial usage of hard materials and vice versa, this work deals with the production, uses and properties of the carbides, nitrides and borides of these metals and those of titanium, as well as tools of ceramics, the superhard boron nitrides and diamond and related compounds.
Author: Elmira Moosavi Khoonsari
Publisher:
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Category :
Languages : en
Pages :
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"The significance of the Na2O-FeO-Fe2O3-CaO-MgO-Al2O3-SiO2 system stems from its applications in industrial processes and natural phenomena. This system in whole or in part was studied for the cooling system of fast breeder reactors, the desulfurization of hot metal and liquid steel, the production of bioactive glasses, coal-combustion slags, the reduction process of bauxite with soda for the production of Al2O3, and the production of solid-state electrodes for electrochemical cells. It also possesses many well-known minerals such as wüstite, spinel, corundum, aegirine, etc. which are of importance in geology. However, phase equilibria in this system are indeed very complex due to the change of Fe oxidation state with oxygen partial pressure and the substitution of Fe3+ by Al3+ in solid solutions. Moreover, the high vapor pressure of sodium, hygroscopicity, high viscosity of SiO2-rich melts, and high fluidity of Na2O- and FeO-rich melts make the experimental study of this system quite challenging. As a result, experimental results in this system were often inconsistent and limited in terms of composition and temperature. Therefore, the construction of a coherent thermodynamic database for the Na2O-FeO-Fe2O3-CaO-MgO-Al2O3-SiO2 system is essential to optimize existing material processes and to develop new processes and advanced materials.All solid and liquid phases of two binaries, six ternaries and two multicomponent sub-systems in the Na2O-FeO-Fe2O3-CaO-MgO-Al2O3-SiO2 system were critically evaluated and optimized in the current study. Using proper thermodynamic models considering the crystal structure of each phase reduces the number of model parameters and thus, enhances the predictive ability of models especially in high order systems. The molten oxide phase was modeled using the Modified Quasichemical Model which takes into account second-nearest-neighbor cation ordering. Extensive solid solutions such as meta-oxides, [beta]"-alumina and pyroxene were treated within the frame work of Compound Energy Formalism with the consideration of their sublattice crystal structures. The wüstite solid solution was modeled using polynomial expansions of the excess Gibbs energy. The sulfide dissolution in the molten oxide phase was modeled using the Modified Quasichemical Model in quadruplet approximation taking into account both first and second-nearest-neighbor short range ordering, simultaneously. Experimental data in the Na2O-FeO-Fe2O3-Al2O3 system were very limited. Hence, key phase diagram experiments and thermodynamic optimization were conducted in this system. Phase diagram experiments were performed using the quenching method followed by Electron Probe Micro-Analysis and X-Ray Diffraction for phase identification. Two- and three-phase equilibria of this system including solid and liquid phases were determined, and the presence of [beta]"-alumina solid solution with a large miscibility gap was revealed for the first time in this work. The developed database was applied to predict the sulfide dissolution in the Na2O-FeO-Fe2O3-CaO-MgO-MnO-Al2O3-SiO2 molten oxide phase which is of high importance for the production of low sulfur steels. Based on the present thermodynamic modeling results, it was shown, for the first time, that the sulfide capacity of Na2O-containing oxide melts is not always a unique property of a given melt composition, and can vary with the gas composition in equilibrium with the oxide melt." --
