Preparation of Ti powder by a mechanical milling induced reduction reaction

摘要

Titanium is produced in large quantities by the Kroll process which involves the eduction of TiCl_4 by Mg at high temperatures. This high temperature reduction reaction can also be accomplished at ambient temperatures by mechanochemical processing which is an application of the mechanical alloying (MA) technique to induce chemical reactions. In the present study Ti has been produced by milling TiCl_4 with Mg or CaH_2. Reduction of TiCl_4 using Mg powder necessitates 40 to 50 hours of milling time for completion of reduction reaction. The milling time was reduced by an order of magnitude by pre-milling of Mg with NaCl to increase surface area and reactivity. Milling time could be reduced further down to few minutes by the use of CaH_2 in place of Mg. Short milling time desceases the contamination pickup during milling to negligible levles. The Ti hydride formed during the reaction minimizes the oxidation of the fine powder product.