On the Equilibrium Among Silicon in Molten Iron Molten Slag and H2-H2o Mixed Gas. (Ii)

A Thermodynamic Model for Representation Reaction Abilities of Structural Units in Full Composition Range of Fe–Si Binary Melts Based on the Atom–Molecule Coexistence Theory

“…The iron‐rich ferrosilicon alloy is one of the important alloys as deoxidizing and alloying agents for molten steel during steel refining processes because Si is one indispensable alloying element in the high‐performance steels, such as transformation induced plasticity (TRIP) steel, etc., as well as in the advanced magnetic materials 1. The thermodynamic properties of Fe–Si binary melts, especially the activity of Si, have attracted tremendous focus in the past several decades since the 1940s 2–49. Turkdogan et al23 and Zaitsev et al43 reviewed the literature on the activity of Si in Fe–Si binary melts prior to 1963 and 2003, respectively.…”

“…Turkdogan et al23 and Zaitsev et al43 reviewed the literature on the activity of Si in Fe–Si binary melts prior to 1963 and 2003, respectively. The major experimental methods for determining the activity of Si in Fe–Si binary melts can be summarized as follows: (i) measuring the distribution ratio of Si between Fe–Si and Ag–Si binary melts through metal–metal equilibrium approach;11, 12, 22, 24, 26, 29 (ii) measuring Si content in Fe–Si binary melts via gas–metal equilibrium method;3, 14, 15, 17, 18, 24, 28, 32, 35, 43 (iii) measuring electromotive force (EMF) by galvanic cell of Si sensor in Fe–Si binary melts;8, 10, 13, 27, 33 (iv) measuring vapor pressure of Fe–Si binary melts at the elevated temperatures;18 (v) measuring the standard equilibrium constant of Fe–Si binary melts equilibrated with SiO 2 ‐containing slags in H 2 –H 2 O atmosphere through metal–slag–gas equilibrium method;4, 5 (vi) determining the partial molar mixing enthalpy change of Si and Fe;30 and (vii) measuring ion current ratio of Fe–Si binary melts through Knudsen cell–mass spectrometer 38. It has been pointed out by Zaitsev et al43 that (1) the metal–metal equilibrium method11, 12, 22, 24, 26, 29 between Fe–Si and Ag–Si binary melts can be used to determine the activity of silicon in Fe–Si binary melts with high Si content, however, this method cannot accurately determine the activity of Si in Fe–Si binary melts with low Si content; (2) the EMF method8, 10, 13, 27, 33 can cause the measured activity of Si in Fe–Si binary melts a little higher because the exchange reactions between the solid electrolyte of silicon sensor and the electrode surface at about 1873 K; (3) the gas–metal equilibrium method3, 14, 15, 17, 18, 24, 28, 32, 35, 43 can be employed to determine the activity of Si in Fe–Si binary melts with reliable accuracy.…”

“…With the development of computing science, the calculation of phase diagrams (CALPHAD) technique1, 40, 42, 44–49 has become an important method to determine the accurate information of Fe–Si binary phase diagram from 298 K to above the liquidus temperatures based on the reported activities2–49 of components in Fe–Si binary melts. However, the investigation of thermodynamic modeling on Fe–Si binary melts at about 1873 K is not sufficient currently.…”

Determination of Activity Coefficients of Elements and Related Thermodynamic Properties of FeSi Binary Melts Based on the Atom–Molecule Coexistence Theory

“…The reaction abilities mainly represented as activity a i of element i in FeSi binary melts have attracted tremendous focus in the past several decades since the 1940s . The main experimental methods for determining activity a Si of Si in FeSi binary melts can be summarized as measuring distribution ratio of Si between FeSi and AgSi binary melts through metal–metal equilibrium approach; measuring Si content in FeSi binary melts via gas–metal equilibrium method; measuring electromotive forces (EMF) by galvanic cells of Si sensor in FeSi binary melts; measuring vapor pressure of FeSi binary melts at the elevated temperatures; (5) measuring standard equilibrium constant of FeSi binary melts equilibrated with SiO 2 ‐containing slags in H 2 H 2 O atmosphere through gas–slag–metal equilibrium method; (6) determining partial molar mixing enthalpy change of Si and Fe; and measuring ion current ratio of FeSi binary melts through Knudsen cell–mass spectrometer . It was summarized by Zaitsev et al that the metal–metal equilibrium method between FeSi and AgSi binary melts can be used to determine activity of silicon in FeSi binary melts with high Si content, but cannot be applied to accurately determine activity of Si in FeSi binary melts with low Si content; the EMF method can cause the measured activity of Si in FeSi binary melts higher because of the exchange reactions between the solid electrolyte of silicon sensor and the electrode surface at high temperature about 1873 K; the gas–metal equilibrium method can be employed to determine activity of Si in FeSi binary ...…”

Activity of MgO in {(1 −x)MgO +xB2O3}, determined by (slag + metal) equilibrium at the temperature 1723 K, using germanium as metal solvent

“…(8)(9)(10)(11)(12) Later, Chou and his co-workers (13,14) used tin as metal solvent in their activity measurements of CaO in the binary slags {(1−x)CaO+xAl 2 O 3 } and {(1−x)CaO+xSiO 2 } at T=1873 K to overcome the experimental difficulties in relation to the iron solvent. In their experiments, the average mole fraction (1−z) of Ca in the alloy {(1−z)Ca+zSn} at equilibrium with CaO-saturated slag was 0.03430.…”