Preparation of Spherical Tungsten Powder by RF Induction Plasma

Abstract:

Spherical tungsten powder was prepared by radio frequency (RF) plasma with irregular tungsten powder as starting material. The effect of feeding rate and particle size on the spheroidization efficiency was studied. The phase composition, morphologies and particle size distributions of the powder before and after spheroidization were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser micron sizer (LMS). The results show that the spherical tungsten powder can be obtained from irregular powder with particle size of 5.5-26.5 μm after RF plasma spheroidization. The powder presents smooth surface and good dispersity, and the spheroidization efficiency is almost 100%. The particle size of tungsten powder is increased slightly after plasma treatment. The spheroidization efficiency of the sample decreases gradually with increasing of the feeding rate. The loose density and powder flowability of tungsten powder are enhanced greatly after RF plasma processing. The loose density is raised from 6.80 g/cm3 to 11.5 g/cm3 and the powder flowability is improved from 14.12 s/50 g to 6.95 s/50 g

Key words:RF plasma; spherical tungsten powder; spheroidization; spheroidization efficiency