Subsolidus phase relations have been determined in the systems SiO2-Cr-O and MgO-SiO2-Cr-O in equilibrium with metallic Cr, at 1100 to 1500℃ and 0 to 2.88 GPa. The results show that there are no ternary phases in the...Subsolidus phase relations have been determined in the systems SiO2-Cr-O and MgO-SiO2-Cr-O in equilibrium with metallic Cr, at 1100 to 1500℃ and 0 to 2.88 GPa. The results show that there are no ternary phases in the SiO2-Cr-O system at these conditions, i.e., only the assemblage eskolaite-Cr-metal-quartz (or tridymite) is found. In the MgO-containing system, however, extensive substitution of Cr2+ for Mg is observed in (Mg, Cr2+)2SiO4 olivine, (Mg, Cr2+)2Si2O6 pyroxene, and (Mg, Cr2+)Cr2O4 spinel. Cr3+ levels in olivine and pyroxene are below detection limits. The pyroxene is orthohombic at XCrPx2+ < 0.2, monoclinic at higher XCrPx2+ . Thestructure of the spinels becomes tetragonally distorted at XCr2+Sp >0.2. The experimental datahave been fitted to a thermodynamic model, and the authors obtained the mixing parameter (W) of Mg-Cr2+ in olivine, pyroxene and spinel, and the relation between temperatures and free energies of formation for the end-members: Cr2+-olivine (Cr2SiO4), Cr2+-pyroxene (Cr2Si2O6) and Cr2+-spinel (Cr3O4).展开更多
The liquid iron containing elements Nb,Mn and Si has been equilibrated with MgO-SiO_2-MnO slag melts at 1600℃ in a Mo wire-wound resistance furnace with a duration of 4h.The oxygen activities in liquid iron were meas...The liquid iron containing elements Nb,Mn and Si has been equilibrated with MgO-SiO_2-MnO slag melts at 1600℃ in a Mo wire-wound resistance furnace with a duration of 4h.The oxygen activities in liquid iron were measured with oxygen sensors.Using the known equilibrium constants of concerning reactions and the oxygen activities in liquid iron,the activities of components in the slag melts can be calculated.It was found that the par- tition ratios of Nb.Mn and Si have a close linear relationship with α_(FeO) in logarithmic scale.The dependence of Nb partition ratio on mole fractions of the slag components was al- so obtained.展开更多
文摘Subsolidus phase relations have been determined in the systems SiO2-Cr-O and MgO-SiO2-Cr-O in equilibrium with metallic Cr, at 1100 to 1500℃ and 0 to 2.88 GPa. The results show that there are no ternary phases in the SiO2-Cr-O system at these conditions, i.e., only the assemblage eskolaite-Cr-metal-quartz (or tridymite) is found. In the MgO-containing system, however, extensive substitution of Cr2+ for Mg is observed in (Mg, Cr2+)2SiO4 olivine, (Mg, Cr2+)2Si2O6 pyroxene, and (Mg, Cr2+)Cr2O4 spinel. Cr3+ levels in olivine and pyroxene are below detection limits. The pyroxene is orthohombic at XCrPx2+ < 0.2, monoclinic at higher XCrPx2+ . Thestructure of the spinels becomes tetragonally distorted at XCr2+Sp >0.2. The experimental datahave been fitted to a thermodynamic model, and the authors obtained the mixing parameter (W) of Mg-Cr2+ in olivine, pyroxene and spinel, and the relation between temperatures and free energies of formation for the end-members: Cr2+-olivine (Cr2SiO4), Cr2+-pyroxene (Cr2Si2O6) and Cr2+-spinel (Cr3O4).
文摘The liquid iron containing elements Nb,Mn and Si has been equilibrated with MgO-SiO_2-MnO slag melts at 1600℃ in a Mo wire-wound resistance furnace with a duration of 4h.The oxygen activities in liquid iron were measured with oxygen sensors.Using the known equilibrium constants of concerning reactions and the oxygen activities in liquid iron,the activities of components in the slag melts can be calculated.It was found that the par- tition ratios of Nb.Mn and Si have a close linear relationship with α_(FeO) in logarithmic scale.The dependence of Nb partition ratio on mole fractions of the slag components was al- so obtained.
