An experimental study of the spheroidization efficiency of induction plasma processes was completed. The main objective being to obtain models which could be subsequently used for the prediction of the spheroidization efficiency for various powders and plasma operating conditions. Silica, alumina, chromium oxide and zirconia powders were treated during the experimentation. For the plasma treatment of the powders the installation used had a maximum available power of 50 kW with an operating frequency of 3 MHz. Operating conditions were varied such to minimize side reactions and the evaporation of powders. The resulting powders did show the presence of cavities and a slight change in the mean diameters. The maximum energy efficiency based semi-empirical model did predict the spheroidization efficiency of the particles beyond a defined critical point known as the maximum energy efficiency point. For the model, the maximum energy efficiency is distinct for the individual powders but remain within a defined range which is reflected in the small variations in the Z constant.

A study is carried out of the spheroidization of ceramic and metallic powders using induction plasma technology. The process is based on the central injection of the powder in the plasma discharge followed by the in-flight cooling and solidification of the molten droplets prior to their collection at the bottom of a stainless-steel water cooled chamber. The degree of spheroidization is evaluated using image analysis. The results are correlated as a function of the powder feed rate, the plasma operating conditions and the thermophysical properties of the powders treated. The model's fit to the obtained experimental data is very good. The results show that the technology can be successfully used for the spheroidization and densification of a wide range of materials.