Thermodynamic modeling of the CoO–SiO₂and CoO–FeO–Fe₂O₃–SiO₂systems

Abstract

A complete critical evaluation and thermodynamic modeling of the phase diagrams and thermodynamic properties of oxide phases in the CoO -FeO -Fe 2 O 3 -SiO 2 system at 1 bar total pressure are presented. Optimized equations for the thermodynamic properties of all phases were obtained which reproduce all available thermodynamic and phase equilibrium data within the limits of absolute experimental accuracy from 25 8C to above the liquidus temperatures at all compositions and oxygen partial pressures. The database of the model parameters can be used, along with software for Gibbs energy minimization, to calculate any type of phase diagram section. Unexplored phase diagram sections and activities of CoO, FeO and SiO 2 in this system of industrial importance are predicted from the thermodynamic models with the optimized parameters.

Experimental Determination of CaO–CrO–Cr2O3–MgO–SiO2 and Thermodynamic Modeling of the CrO–Cr2O3–MgO–SiO2 System

“…(C) Olivine: The extensive solubility of chromium oxide in the olivine was modeled using the two sublattice compound energy formalism 42 . The model has been used for the Mg 2 SiO 4 –Ca 2 SiO 4 , 18 Mg 2 SiO 4 –Fe 2 SiO 4 , 43 and Fe 2 SiO 4 –Co 2 SiO 4 44 olivine solutions. Because the cations can occupy two different octahedral sites, called M1 (smaller size) and M2 (larger size), the phase is modeled as [Mg 2+ ,Cr 2+ ] M2 [Mg 2+ ,Cr 2+ ] M1 [Si 4+ ][O 2− ] 4 .…”

Floating-zone growth and characterization of single crystals of cobalt orthosilicate, Co2SiO4

“…Zabdyr et al [21] published in 2003 results of a modeling of the phase equilibria in the CoO-SiO 2 system performed using the CALPHAD approach; these authors adopted 1417 1C as the melting temperature of Co 2 SiO 4 in air at atmospheric pressure. In 2007 Jung et al [22] adopted a value of 1410 1C for the melting temperature of Co 2 SiO 4 at 1 atm total pressure at a variety of oxygen activities ranging between that of air at 1 atm total pressure and that corresponding to the equilibrium between metallic cobalt, cobalt silicate and melt.…”

Thermodynamic reevaluation of the Fe–O system

“…Metallic melt was modeled as a separate solution [24]. This oxide liquid was further used in many higher-order systems [25][26][27][28][29] as part of the large FactSage Slag database [30].…”