Consolidation behavior of Mo powder fabricated from milled Mo oxide by hydrogen-reduction

Nano-sized Mo powder was synthesized by ball-milling and subsequent hydrogen-reduction of MoO 3 powder. The crystalline size of the MoO 3 powder was decreased to below 10 nm by a 20 h ball-milling process. Hygrometric measurement was performed to understand hydrogen-reduction behavior of MoO 3 with different milling time. The peak temperature for the reduction was shifted to lower temperatures by increasing the milling time. The peak for the reaction of MoO 3 → MoO 2 was more effective than that for the reaction of MoO 2 → Mo. This result is due to the transformation steps for the reaction of MoO 3 → MoO 2 take place via chemical vapor transport (CVT) by generation of a gaseous transport phase. After hydrogen-reduction at 800 °C, the crystalline size of the Mo powder was about 60 nm. The sinterability of the nano-sized Mo powder was considerably enhanced compared with that of a commercial Mo power.