China Nonferrous Metallurgy

Vacuum induction melting gas atomization technology (VIGA technology) is the mainstream atomization technology for preparing high-performance spherical metal and metal alloy powders by gas atomization method. However, the details of closely coupled gas atomization mechanism are still unclear and lack of core theory. Due to the gas-liquid coupling during the VIGA powder production process in a closed and high-temperature environment, it is difficult to observe the details. This article simulates the preparation of Cu-Al-Ni alloy powder using VIG technology under different atomization pressures. Based on CFD technology, Fluent software is used to model the interaction between gas-liquid two-phase flow during the atomization process, simulating the primary and secondary crushing processes of copper aluminum nickel alloy melt under different atomization pressures during the atomization process. The simulation results show that the atomization pressure increases from 6MPa to 8MPa, the maximum velocity of the flow field increases from 470m/s to 520m/s, and the static pressure at the end of the delivery tube increases from -30kPa to 40kPa. During the primary atomization process, there is a pressure gradient in the radial pressure of the delivery tube port. The melt flows out of the delivery tube to form a liquid film, which is broken into initial droplets by the airflow at the junction of the reflux zone and the airflow expansion zone. The higher the atomization pressure, the smaller the initial droplets; the secondary atomization process is that the initial droplets continue to break, and the particle size of the powder is within 20~100μm, as the atomization pressure increases, the median particle size of the powder decrease, but the decrease is not significant; the design of VIGA equipment nozzles have a critical value, and after reaching the critical value, the various values in the flow field do not change significantly. Therefore, the reduction of powder particle size is not significant between 7MPa and 8MPa.