Comparison of gas atomization on A6060 Al alloy powders produced by internal and external mixing type nozzles

Abstract

MAM (Metal additive manufacturing) is a technology that produces three-dimensional parts layer by layer from metal powders. Most of metal powders for MAM are produced by gas atomization processes due to its flowability and purity. Related studies have shown the benefits of using gas-atomized metal powder in recent years. Although gas atomization process are commercially used in metal powder production for century, studies for gas-atomized Al powder are quite rare. The goal of this study was to design a novel internal-mixing type atomizer for producing Al alloy powders, and to compare it performance with that of external-mixing type nozzle. In this paper, a nozzle designed with internal prefilming mechanism is first proposed and characterized. Comparison of performance of internal and external-mixing nozzle on Al alloy powder production is then further introduced. To compare the performance of the nozzle design of external and internal-mixing, HPGA (High Pressure Gas Atomization) nozzle is used as external-mixing nozzle in this study. All the gas-atomized metal powders in this paper were screened by a 60-mesh sieve, and then were measured by Beckman Coulter LS230 particle sizer. Results show that the particles size of the gas-atomized Al alloy powders decreases as the atomization pressure was increased. Mean particle size (Dv50) of 18.0 μm is achieved in the test with Al alloy. The SEM micrograph of the metal powder shows that the sphericity of the particle is better than that produced by external-mixing type nozzle.