An industrially feasible pathway for preparation of Mo nanopowder and its sintering behavior

In this study, a low-cost, efficient and industrially feasible pathway was developed to prepare Mo nanopowder via a two-stage carbothermic reduction of commercial MoO₃ with carbon black at 600 °C and 1050 °C, respectively, followed by deep hydrogen reduction at 800 °C. The sintering behaviors of the prepared Mo nanopowder and micron commercial Mo powder containing different amounts of Mo nanopowder were investigated in the temperature range of 1000 °C–1600 °C. At 1200 °C, the Mo nanopowder was sintered to near-fully densified compact with a relative density of about 95.8%, which was much higher than the value of 70% for commercial Mo powder. For the nanopowder, the grain size dramatically increased when the sintering temperature increased. The hardness of sintered nanopowder at 1200 °C (relative density, 95.8%; average grain size, 1.88 μm) was about 254 HV0.1, which was much higher than the value of 182 HV0.1 as sintering commercial micron sized Mo at 1600 °C (relative density, 93.9%). The addition of Mo nanopowder into micron Mo can noticeably activate its sintering and improve its hardness.