Preparation and Consolidation of Molybdenum Nanopowder

Abstract

Recently, the sintering of nanopowder has been focused because it can be manufactured at much lower temperature. Nanopowder has large portion of surface area and it means increase in driving force to sintering. In this research high-energy ball milling and hydrogen reduction of molybdenum trioxide powder were applied to fabricate molybdenum nanopowder. Sintering behavior of molybdenum nanopowder was different from that of commercial powder. When the Mo nanopowder was sintered at 1200oC for 1 h, it showed significant improvement in mechanical properties such as 95% of theoretical density, 1.4 ?m of grain size, and 2.34GPa of microvickers hardness. However, during the conventional sintering, rapid grain growth in final stage sintering was inevitable. Thus two-step sintering was introduced to suppress grain growth. Microvickers hardness was increased up to 3.15GPa and grain size was 0.5 ?m by two-step process