Preparation of Molybdenum Nanopowders by Hydrogen Reduction of Ball-Milled Molybdenum Oxide Powder

Abstract

Metallic molybdenum (Mo) powders have been generally fabricated by reduction process of Mo oxides. Mo is a well-known refractory metal, which needs relatively high temperature over 1800-2000oC for full-densification. Thus, in the low-energy process point of view, decrease of sintering temperature has been required. In this study, Mechanochemical process (MCP), which consists of a ball-milling of oxide powders and a subsequent hydrogen-reduction, are combined to obtain a nanostructured Mo metallic powder, of which the extended surface area can enhance its sinterability. The crystalline size of MoO3 powders decreased by the ball-milling process; it reached below 10 nm by ball-milling of 20 h. The nanostructured metallic Mo powders, of which mean crystalline size was about 60 nm, could be fabricated through hydrogen reduction process at 800oC with the heating rate of 10oC/min. These nanostructured Mo powder compared with commercial Mo powder shows enhanced sinterability.