Equilibrium of calcium vapor with liquid iron and the interaction of third elements

Abstract

The dissolution equilibrium of calcium vapor in liquid iron was carried out at 1873 K in a two-temperature zone furnace using a vapor-liquid equilibration method. A sealed Mo reaction chamber and a self-made CaO crucible were used in this study. The thermodynamic parameters obtained are as follows.

For reaction Ca (g)=[Ca],

$$ln K = 4.27 - 15,040/T \Delta G^ \circ = 125,000 - 35.5T {J \mathord{\left/ {\vphantom {J {mole}}} \right. \kern-\nulldelimiterspace} {mole}}$$

The relation between dissolved calcium in liquid iron and calcium vapor can be expressed as

$$[pct Ca] = 0.0235 P_{Ca} /(1 - 0.305 P_{Ca} )$$

The interaction parameters of third elements on calcium determined at 1873 K are as follows:

$$\begin{gathered} e_{Ca}^{Ni} = - 0.097 \pm 0.007, e_{Ca}^{Cr} = - 0.18 \pm 0.02, e_{Ca}^{Ti} = - 0.13 \pm 0.009 \hfill \\ e_{Ca}^{Si} = - 0.11 \pm 0.005, e_{Ca}^V = - 0.15 \pm 0.015, e_{Ca}^{Mn} = - 0.10 \pm 0.013 \hfill \\ e_{Ca}^{Cu} = - 0.023 \pm 0.003, e_{Ca}^{Sn} = - 0.026 \pm 0.003 \hfill \\ e_{Ca}^{Sb} = - 0.043 \pm 0.005, e_{Ca}^{Bi} = - 0.15 \pm 0.035 \hfill \\ \end{gathered} $$