Thermodynamic assessment of the CaO-MgO-SiO2 system

Huang, Weixiong; Hillert, Mats; Wang, Xizhen

doi:10.1007/bf02671244

Cited by 69 publications

(52 citation statements)

References 36 publications

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“…Two-sublattice Thermo-Calc [21] T m (CaO) = 2900 °C [22] CaO-rich part: [23] Miscibility gap: [24], [25] [26], [27], [28] Modified quasichemical FactSage [1], [29] T m (CaO) = 2572 °C [30] Miscibility gap: [24], [25] [31], [13] Cellular Mtdata [21] T m (CaO) = 2900 °C [32] CaO-rich part: [23] Miscibility gap: [24], [25] [33] Two-sublattice Thermo-Calc [45] Liquidus: [46], [47], [48], [49], [50] Field of mullite: [51], [52], [53], [54] [55]…”

Section: Systemmentioning

confidence: 99%

CALPHAD formalism for Portland clinker: thermodynamic models and databases

et al. 2011

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International audienceThe so-called CALPHAD method is widely used in metallurgy to predict phase diagrams of multi-component systems. The application of the method to oxide systems is much more recent, because of the difficulty of modelling the ionic liquid phase. Since the 1980s, several models have been proposed by various communities. Thermodynamic databases for oxides are available and still under development. The purpose of this article is to discuss the distinct approaches of the method for the calculation of multi-component systems for Portland cement elaboration. The article gives a state of the art of the most recent experimental data and the various calculations for the CaO-Al2O3-SiO2 phase diagram. A literature review of the three binary sub-systems leads to main conclusions: (i) discrepancies are found in the literature for the selected experimental data, (ii) the phase diagram data in the reference books are not complete and up to date and (iii) the two-sublattices model and the modified quasichemical model can be equally used for the modelling of the aluminates liquid. The predictive feature of the CALPHAD method is illustrated using the CaO-Al2O3-SiO2 system with the two-sublattices model: extrapolated (predicted) and fully-assessed phase diagrams are compared in the clinkering zone of interest. The recent application of the predictive method for the calculations of high-order systems (taking into account Fe2O3, SO3, CaF2, P2O5) shows that the databases developed with the two-sublattices model and the modified quasichemical model are no longer equivalent

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Section: Systemmentioning

confidence: 99%

CALPHAD formalism for Portland clinker: thermodynamic models and databases

et al. 2011

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“…Para ello, se utilizará sucesivamente la información suministrada por los sistemas binarios SiO 2 -CaO [23,24] y SiO 2 -MgO [25,24] y del sistema ternario SiO 2 -CaO -Al 2 O 3 [26,24].…”

Section: Refractarios De Síliceunclassified

“…Para encontrar la respuesta hay que recurrir al sistema SiO 2 -MgO [25,24]. En este sistema, la sílice es termodinámicamente Sin embargo, como se puede apreciar, el campo de estabilidad de la tridimita, que por las razones expuestas anteriormente es la fase polimórfica de la sílice que interesa obtener en el material, se extiende hasta la temperatura de 1.470 o C. Estando esta por debajo de la primera formación de fase líquida, la cual tiene lugar a 1.543 o C. Este hecho dificulta seriamente la transformación polimórfica del cuarzo (β) a tridimita, que tendría que tener lugar en estado sólido, evitándola, y justificando que el MgO no pueda usarse como aglomerante de la sílice.…”

Section: Fase Polimórficaunclassified

Los diagramas de equilibrio de fases como una herramienta para el diseño y comprensión del comportamiento en servicio de los materiales refractarios

Aza¹,

Pena²,

Caballero³

et al. 2011

Bol. Soc. Esp. Ceram. Vidr.

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La aplicación de los diagramas de equilibrio de fases para diseñar materiales refractarios y también para comprender su comportamiento en servicio, ha sido, a lo largo del tiempo, un tema de controversia en el campo de la cerámica y de los refractarios. Sin embargo, en la tecnología refractaria moderna es posible obtener mezclas homogéneas a través de rutas sofisticadas de procesamiento. Como resultado, las velocidades de reacción son generalmente lo suficientemente altas para alcanzar el equilibrio o cuasi-equilibrio durante la cocción convencional del material así como en su comportamiento en servicio. Por lo tanto, hoy en día, los diagramas de equilibrio son válidos no sólo para determinar la tendencia termodinámica de equilibrio durante la cocción del material refractario, sino también para predecir el estado final de equilibrio y, con una buena comprensión de las relaciones de equilibrio, también es posible conocer el camino a través del cual el sistema refractario evoluciona hacia el estado final durante su aplicación. En consecuencia, los diagramas de equilibrio son una potente herramienta para el diseño de nuevos materiales refractarios, así como para una mejor comprensión de su comportamiento en servicio en condiciones de alta temperatura y agentes corrosivos. En el presente trabajo se pretende mostrar, a través de algunos ejemplos pertinentes, cómo el proceso de fabricación de algunos materiales refractarios tradicionales puede ser explicado y también cómo es posible mejorar y / o diseñar nuevos materiales refractarios mediante el uso de los diagramas de equilibrio de fases apropiados. El presente trabajo recopila y revisa la última conferencia plenaria impartida por el Profesor Salvador De Aza sobre el tema. The phase equilibrium diagrams as a tool for the design and use of refractoriesRefractories are complex materials used at high temperature, in severely corrosive atmospheres and in contact with aggressive liquids. The high temperatures imply that such systems tend to equilibrium and this is frequently attained during service; at least local equilibrium is achieved. This allows the basic principles of phase diagrams to be used in this technology. Traditionally, refractories have been designed to be close to equilibrium so that in-service changes were restricted. Currently, additions of raw materials are often made that will react in use, in a controlled manner, to give favorable effects under the service conditions. Equilibrium diagrams are valid not only for determining the thermodynamic tendency but also for predicting the final equilibrium state and to know the way through which the material moves into the final state. In this context equilibrium diagrams become a powerful tool for a better understanding of the behavior of refractrories during service. After a general consideration on the importance of phase equilibrium diagrams in this field, criteria for using equilibrium diagrams, as a tool for improving traditional refractories and/or designing advanced or new refractories, will be given. P...

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“…In the Fe-O-Si system, fayalite, with the formula 2FeO⅐SiO 2 , has the same crystal structure and thus, olivine has its end compounds fixed by these two systems. The phase is described with the formula (Ca +2 ,Fe +2 )(Ca +2 ,Fe +2 )(Si +4 )(O Ϫ2 ) 4 . The two sublattices with Ca +2 and Fe +2 , to be denoted by I and II, respectively, are structurally different and Ca +2 prefers one of them, here, denoted by II.…”

Section: Thermodynamic Modelsmentioning

confidence: 99%

“…The Fe-O system was evaluated by Sundman. [1] The CaO-SiO 2 system was evaluated by Hillert et al [2,3] and reassessed by Huang et al [4] The Ca-Fe-O system was assessed by Hillert et al [5] and later modified together with the Fe-O system by Selleby and Sundman. [6] The Fe-O-Si system was evaluated simultaneously with the present work and is presented in a separate article.…”

Section: Introductionmentioning

confidence: 99%

An assessment of the Ca-Fe-O-Si system

Selleby

1997

Metall Mater Trans B

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The thermodynamic properties of the Ca-Fe-O-Si system have been studied with particular emphasis on the slag system CaO-FeO-Fe 2 O 3 -SiO 2 . One of the subsystems, Fe-O-Si, was evaluated simultaneously to be able to take into account the higher order information from the present system. The assessment was succeeded by a study of different modifications of the ionic two-sublattice model that was used to describe the liquid phase. This model allows description of the slag and the liquid metal with one set of parameters. A model has been chosen which is optimal with regard to the fit of experimental data, compatibility with related systems, and number of parameters needed. The assessment is based on recent evaluations of the subsystems. All the solid-solution phases have been described using the compound-energy model.

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Thermodynamic assessment of the CaO-MgO-SiO2 system

Cited by 69 publications

References 36 publications

CALPHAD formalism for Portland clinker: thermodynamic models and databases

CALPHAD formalism for Portland clinker: thermodynamic models and databases

Los diagramas de equilibrio de fases como una herramienta para el diseño y comprensión del comportamiento en servicio de los materiales refractarios

An assessment of the Ca-Fe-O-Si system

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