Enhanced Sintering Process of Molybdenum Nanopowder

Abstract

Molybdenum is useful for various industrial fields in high temperature and high pressure environment such as aircraft parts, electrical contacts, and filaments. In the previous research, the nano-sized Mo powder was fabricated by high energy ball-milling and subsequent hydrogen reduction. The densification over 90% of theoretical density could be obtained by the pressureless sintering of Mo nanopowder at 1300oC with 1.0μm in grain size and the 2.43GPa in hardness. However particle size refinement caused massive amount of grain growth. Therefore in this study, two-step sintering was introduced to the densification of Mo nanopowder to obtain sintered body with ultra fine grain. The two-step sintering process led to restrain grain growth to 0.5 μm and to consequently improve hardness up to 3.15GPa even though the density was 90% of theoretical value. And then mechanical properties by each sintering method were evaluated through Vickers hardness test.