Graduate School of Engineering
Department of Metallurgy

Metallurgical Process Engineering(Prof. Nagasaka)

Research Topics

Thermodynamic Prop erties and Phase Relation of Two Liquid Phase Slag

Phase equilibria of two-liquid CaO-MgO-FetO-P2O5 slag saturated with (Mg,Fe)O solid solution and the distribution ratio of phosphorus between the slag and liquid iron were measured at steelmaking temperatures by chemical equilibration. It is unknown that this slag system has wide liquid miscibility gap at steelmaking temperature and this two-liquid phase slag has many advantages, such as high activities of both FetO and CaO and high amount of phosphoric oxide. It was made clear that the phosphorus distribution ratio between the slag system and molten iron was higher than that of the CaOsat.-FetO-P2O5 system and the two-liquid slag phase was very useful for dephosphorization of molten steel and reduction of slag volume. Presently, effect of SiO2 addition on phase relation is in progress.

Formulation on Deoxidation Equilibria of Molten High Alloys with Quadratic Formalism and Redlich-Kister Type Polynomial

Relation between the activity coefficient expressed by Darken's quadratic formalism and the excess Gibbs energy change of mixing has described with Redlich-Kister type polynomial was discussed on Si deoxidation of Fe-Ni, Ni-Cu and Ni-Co alloys. The activity coefficients of Si and O in metal expressed by quadratic formalism have been converted into formula using interaction parameters Ωi-j under the condition where concentration of Si and O are dilute. Numerical analysis on Si deoxidation of molten Fe-Ni, Ni-Cu and Ni-Co alloys has been carried out. It has been found to be outstanding in the agreement of equilibrium Si and O contents in molten Fe-Ni, Ni-Cu and Ni-Co alloys alloy formulated in the present work with the experimental results. The deoxidation equilibrium of not only one component metal but also alloy can be formulated. Formulation of deoxidation equilibrium of other systems will be conducted in the future.

Enhancement of photosynthetic CO2 fixation by marine phytoplankton with steelmaking slags as a nutrient source

Suppression of CO2 and waste such as slags discharged from iron- and steelmaking processes are some of the typical major issues for the protection of global environment and sustainable growth of steelmaking industry. Utilization of active phytoplankton growth will be one of the best options to stabilize and suppress carbon dioxide at high-efficiency. Inorganic minerals such as C, O, N, Si, P and Fe are necessary for phytoplankton multiplication. It is crucial for supply of nutrition into seawater effectively for phytoplankton multiplication to understand the dissolution behavior of some elements from steelmaking slags into seawater. We are now investigating on the following subjects. They are morphology of the precipitated phases in steelmaking slags during cooling period, the dissolution behavior of some elements from steelmaking slags into artificial seawater, and the effect of nutrient dissolved into seawater on phytoplankton multiplication.

Fig. 1

Fig. 1

Fig. 2:SEM microstructure of an in-situ synthesized alumina matrix composite

Fig. 2