Sintering kinetics analysis of molybdenum nanopowder in a non-isothermal process

Abstract

Compared with commercial micro-sized molybdenum powder, the sintering of molybdenum nanopowder fabricated by high-energy ball milling and subsequent hydrogen reduction was considerably more activated due to its extended surface area. In this study, the sintering kinetics of a molybdenum nanopowder were evaluated by measuring the linear shrinkage in a non-isothermal process and calculating the activation energy for the initial sintering stage. To reach a linear shrinkage of 2 %, the activation energy of the molybdenum nanopowder sintering was 180 kJ, primarily due to the grain boundary diffusion, while the activation energy of the commercial micro-sized powder sintering was 345 kJ, predominantly due to the volume diffusion.

Controllable Preparation of Spherical Molybdenum Nano-Powders by One-Step Reduction of APM in Radio Frequency Hydrogen Plasma

“…The molybdenum powders prepared by the hydrogen reduction method usually have large particle sizes of several microns because the molybdenum nucleation and growth process are difficult to control [ 5 , 6 ]. In addition, the sintering temperature of the micron-molybdenum powder must reach 1800–2000 °C and be maintained for several hours to obtain 90% of its theoretical density; the grain size of the compact is tens of microns [ 7 , 8 , 9 ]. Studies have shown that Mo nano-particles can be sintered at 1200 °C for one hour to prepare compacts over 95% of their theoretical density with an average grain size of 1.4 μm [ 10 ].…”