Evaluation of spheroidized tungsten carbide powder produced by induction plasma melting

R.M Dire,K Premlall,D Delport,H Bissett

doi:10.17159/2411-9717/1352/2021

Abstract

SYNOPSIS Tungsten carbide is a fine grey powder. It can be formed into shapes by compacting with the addition of a binder. Spherical particles are generally preferred in additive manufacturing as they pack together more efficiently than non-spherical particles, promoting a uniform powder bed density, better flowability, and elimination of internal cavities and fractures, resulting in a better quality of final product. The particle shape of powders can be transformed into spherical through the process of spheroidization. However, due to its high melting point, tungsten carbide could be difficult to spheroidize. Tungsten carbide was spheroidized using an inductively coupled radio frequency plasma at various plate powers between 9 and 15 kW. The influence of additional H2 in the sheath gas on the chemical composition of the tungsten carbide product was also investigated by means of XRD, which indicated that WC is converted to W2C at higher H2 concentrations. Optical analysis of SEM micrographs indicated that the spheroidization ratio increased with increased plasma energy. Keywords: spheroidization, induction plasma melting, tungsten carbide.

Highlights

Tungsten carbide is a chemical compound used for various high-temperature applications
The fraction of evaporation for all experiments was low (< 4%), which can be attributed to the high boiling point (6 000°C) of tungsten carbide (Gignard, 1998)
In this instance, melting of the particle surfaces, partial melting of the particles, and sintering of fine and larger particles occurred. Once these particles exit the plasma tail flame, rapid quenching of the oval and sintered particles occurs, resulting in a decreased spheroidization ratio compared to the feed powder

Summary

Introduction

Tungsten carbide is a chemical compound used for various high-temperature applications. Tungsten carbide was spheroidized using an inductively coupled radio frequency plasma at various plate powers between 9 and 15 kW. The particle shape of powders can be transformed into spherical by the process of spheroidization.

Results

Conclusion