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

Abstract

Spherical molybdenum nano-powders were in-situ ultrafast synthesized from ammonium paramolybdate (APM) raw materials in a one-step reduction method by radio frequency (RF) hydrogen plasma. Due to the extreme conditions of the RF plasma torch such as its high temperature and large temperature gradient, the injected raw APM powder was quickly gasified and then reduced into nano-sized metal molybdenum (Mo) powder. The influences of APM powder delivery rate and H2 concentration on the properties of the obtained powders were investigated. Field-emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X-ray diffraction (XRD), nanolaser particle analyzer, and specific surface area method were used to characterize the morphology, phase, and particle size distribution of the powders. The results showed that the nano-sized Mo powder obtained by hydrogen plasma treatment had a quasi-spherical morphology and an average particle size of about 30 nm. The particle size could be successfully adjusted by varying H2 concentrations. In addition, spherical nano-sized MoO3 powder could be obtained when no H2 was added into the RF plasma.

Synthesis of Spherical β-Quartz Solid-Solution Particles Derived from Cordierite Using a Flame Process

“…Over the past several years, numerous methods have been reported for the fabrication of spherical particles based on the use of high-temperature heat sources, such as radio-frequency thermal plasma − and flame process. − However, plasma-based techniques are limited because plasma torches cannot easily be enlarged and require high energy inputs. For these reasons, as a unique, rapid, single-stage, and cost-effective process, the flame spheroidization process has a more promising chance for the large-scale manufacture of spherical particles.…”