Complex deoxidation with calcium-silicide was made in pure iron melted with a high frequency furnace. Kinetics of the deoxidation process was analyzed to evaluate the growth rate and the separation rate of the primary inclusion. The compositions of the deoxidation products were determined by X-ray microanalyzer.
The experimental results are as follows:
1) Calcium-silicide reacts effectively as the deoxidizer when the atmospheric pressure on the melt is kept higher than the vapour pressure of calcium.
2) In the initial stage of deoxidation with calcium-silicide, the content of oxygen in liquid iron is remarkably decreased by the formation and the floating up of such primary inclusions as Feo-SiO₂ and CaO-SiO₂.
3) There after a number of fine silica particles remain in liquid iron without separation. Consequently the rate of deoxidation becomes smaller with the lapse of time.
4) The deoxidation behaviour caused by calcium silicide is clarified in relation to the change in the content of oxygen in liquid iron and the change in the size of inclusion.
5) Oxide inclusions formed in liquid iron are classified into the following four types, e. g. FeO-SiO₂, CaOSiO₂ containing a large amount of FeO, CaO-SiO₂ including a small amount of FeO and fine SiO₂.