Preparation of Pure Ti Nanopowders by High-Energy Ball Milling and Dehydrogenation of TiH₂

Due to the characteristics of a high strength-to-weight ratio, superior corrosion resistance, good specific strength, and forming a lightweight alloy of titanium (Ti), the fabrication of high-purity Ti has consistently attracted attention, which is technological importance for a wide range of applications such as the aerospace industry, orthopedic, and dental implant materials. However, its susceptible oxidative characteristics and high-yield strength restrict the manufacturing of pure Ti through casting and cold working. Therefore, the powder metallurgy process is widely used in the production of Ti, but it has been difficult to prepare a pure Ti powder with suppressed oxidation. In this regard, we focus on the production of ultra-fine and pure Ti powders with low oxygen content through milling and dehydrogenation using brittle titanium hydride (TiH₂). We perform a high-energy ball mill (HEBM) using a planetary system to refine micron-sized TiH₂ powders by varying the milling speed, ball size, and time. The optimum condition for TiH₂ milling is determined by analyzing the particle size and lattice strain of the milled powders. The effect of particle size on dehydrogenation is investigated by thermal analysis with a heating rate of 5^oC/min under an argon atmosphere. In addition, the effect of the reducing agent added during the dehydrogenation heat treatment process on the change in oxygen content of the synthesized Ti powder was analyzed. By optimizing the milling conditions, TiH₂ particles with a minimum size of 195.9 nm were obtained, and the dehydrogenation temperature decreased up to 140^oC as the particle size decreased. In this work, we provide a promising technique for synthesizing the ultra-fine pure Ti powder which is important for the military industry and precursor elements for alloys and compounds.