Spheroidization and Densification of Nickel Powders by RF-Induction Plasma

摘要

Spheroidization or densification of irregular or porous powders is one of themain applications of RF-induction plasma. In the present paper, the experimental results were reported on the induction plasma spheroidization and densification of three types of irregular nickel powders produced by hydrogen reduction in an organic solution. The studied process parameters included powder feed rate, carrier gas flow rate and feeding lance position. All of those parameters were found to have significant effects on the efficiencies of powder spheroidization and densification. The experimental results were discussed in association with the thermal efficiency of the present plasma system. The enthalpy estimation of different gas mixtures calculated with SOLGASMIX program and the mathematical modelling results from literatures were used in depicting the thermal behaviors of nickel powders in the torch. Due to the strong coupling phenomena in the plasma-particle system, fine adjustment of different operating parameters was important for sustaining a stable plasma and for achieving a better thermal efficiency of powder spheroidization and densification.