CO<SUB>2</SUB>-Ar混合ガスによる溶鉄の脱炭と共存元素の酸化について On the Rates of Decarburization and Oxidation of Molten Iron Alloys with CO<SUB>2</SUB>-Ar Atmosphere

The rates of decarburization of molten iron, containing Si, Cr and Mn, with CO<SUB>2</SUB>-Ar mixtures at 1600°C were measured, and the oxidations of the above-mentioned elements were also investigated. It was observed that the carbon concentration decreases linearly with time down to the critical value, C<SUB>f</SUB>, where the oxide film appears on the surface of melt, and that the value of C<SUB>f</SUB> increases with the amount of added elements and the partial pressure of CO<SUB>2</SUB>. The critical value C<SUB>f</SUB> depends on the deoxidizing force of added elements. Carbon concentration on the reaction interface, Ci, corresponding to C<SUB>f</SUB>, calculated from the equilibria, Me+O=(MeO) and C+O =CO, was used to estimate the thickness of diffusion layer in metal surface. Before the oxide film appears on the surface of melt, the rates of decarburization was proportional to the partial pressure of CO<SUB>2</SUB> and independent of the amount and the kinds of added elements.