Effect of processing parameters on microstructure and properties of spherical WC-Co powder by plasma spheroidization

In this study, radio-frequency plasma spheroidization was used to obtain spherical WC-Co powder from granulated WC-Co powder using different parameters. The results show that the spheroidization ratio of the powder first increased and then decreased with an increase in plasma power, whereas the trend of the average particle size is the opposite. The spheroidization ratio of the powder decreased with an increase in the powder feeding rate, whereas the average particle size increased. This also indicates that cobalt loss and WC decomposition occurred during plasma spheroidization. The loss of cobalt increased continuously with increasing plasma power and decreasing powder feeding rate. Black and white particles with significantly different carbon distributions were observed in the spheroidized powder, which were mainly caused by the different degrees of WC decomposition. The flowability and apparent density of the spheroidized WC-Co powder were positively correlated with the ratio of black to white particles.