Вдосконалення високочастотного індукційно-плазмового технологічного процесу сфероїдизації алюмінієвого порошку

This study explores the process of the inductively coupled plasma spheroidization of aluminum powder. The task addressed relates to the complexity of spheroidization of low-melting materials, as well as to the growing need to use spheroidized powders from new materials in additive manufacturing, powder metallurgy, and gas-thermal coating. To define the process of particle spheroidization, a comprehensive approach was used, including experimental studies, analytical description of thermal processes, and numerical modeling using the COMSOL Multiphysics software environment. Based on the simulation results, parameters of the inductively coupled plasma, the regularities of heating, melting and crystallization of aluminum powder particles were determined. It was found that the full cycle of heating to the melting temperature and phase transition occurs over an extremely short time – on the order of 10-5 s to 10-4 s for a particle with a diameter of 50 μm. The temperature gradients inside the particles are insignificant, which contributes to their uniform melting and the formation of a spherical shape under the influence of surface tension forces. The key factors of the process are the plasma temperature and the time the particles spend in the high-temperature zone. The simulation results made it possible to establish technological modes of spheroidization: inductor current 40–42 A, current frequency 1.76 MHz, gas flow rate 5 l/s, gas pressure at the plasmatron inlet 13×10-3 МPa. The adequacy of the proposed modeling was confirmed by obtaining aluminum powder with a high degree of spheroidization (from 95% to 98%). The model built could be used to predict the process parameters and its further optimization in order to obtain spherical powders from other materials and fractions