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A process to produce titanium powder continuously is proposed and its applicability is examined experimentally. The method is based on the chemical reaction in the conventional Kroll reduction process; however, TiCl 4 gas is injected into molten salt on which a molten magnesium layer is floated as the reductant. Bubbles of gaseous TiCl 4 can be reacted at the lower surface of the liquid Mg layer, while TiCl 4 gas reacts on the upper surface in the Kroll process. The fine Ti particles produced in this study were well separated from magnesium and could be recovered from the bottom of the molten salts. The particles were small and fine enough for use in powder metallurgy, while congregated lumps of about 20 m in size are obtained by the Kroll process. The composition of molten salts and an operation temperature above 1073 K did not affect the morphology of the Ti particles, if suitable material for the reaction vessel was chosen.

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A process to produce titanium powder from Ti 2ϩ in the molten salt was confirmed experimentally. It consists of two steps. In the first step, titanium (IV) chloride gas dissolves in the molten salt as the titanium (II) chloride by reacting chemically with the metallic titanium or magnesium. In the second step, this molten salt is exposed to the metallic reductant Mg for the final reduction to the metallic Ti powder. Experimentally, the feed of TiCl 4 gas and the subsequent reaction with Ti prepared the molten salt containing 5 to 10 mass pct Ti 2ϩ . By Mg reduction of this salt, the well-isolated fine Ti particles were recovered. The powder morphology and particle size depended on the Ti 2ϩ concentration, reduction temperature, time, and concentration of the by-product MgCl 2 . The stirring by argon gas bubbling effectively grew the fine and round particles to a few tens of microns in size.

The crystallization behavior of CaO-Al2O3-MgO oxide powder which is one of the major non-metallic inclusions in Al-killed steel was systematically examined in the present study. 33mass%CaO-62mass% Al2O3-5mass%MgO and 30mass%CaO-57mass% Al2O3-5mass%MgO-8mass%Li2O glass powders were heat-treated at 1 073-1 673 K for 8-512 s under air.CaO-Al2O3-MgO glass was found to be crystallized immediately after the heat treatments. Moreover, it was revealed that the addition of Li2O accelerated the crystallization of the glass powders, and controlled aggregation of crystal particles. Additionally, the indentation hardness of crystallized glasses after 512 s heat-treatments was investigated by using a nano-indenter. The addition of Li2O had the effect of lowering the hardness of samples, which indicates that Li2O would improve the deformation behavior of aluminate based inclusions.