Fabrication of spherical WC-Co powders by radio frequency inductively coupled plasma and a consequent heat treatment

To obtain spherical cemented carbide powders suitable for the additive manufacturing process, granulated WC-Co powders made by spray drying were spheroidized by radio frequency inductively coupled plasma. The influence of powder feed rate on the sphericity of the obtained powders was investigated. Results show that spheroidization efficiency of near 100% was achieved at different applied feed rates. Applying plasma processing decreased the particle size, compacted the microstructure and caused obvious improvements in the apparent density and flowability. However, complete decomposition of WC and certain evaporation loss of Co were noted in these powders. The spheroidized powders consisted of W2C, C, Co3W3C, and contained higher Co at a higher applied feed rate. After conducting heat treatment at 950 °C for 3 h, the powder phase composition was regenerated as WC and Co. The heat-treated powders, due to their good sphericity, improved apparent density and flowability are suitable for the printing processes.