Effect of Particle Size, Lubricant, and Heat Temperature on the Flowability of Ni-Based Powders for Additive Manufacturing

Abstract

Gas-atomized Ni-based powder tends to agglomerate, directly impacting the spreadability of printing process. In this paper, three technical methods are applied to restore the powder flowability, including regulating particle size distribution, lubricant modification, and heating treatment. As particle size increases, powder regains flowability. However, the average particle size of GH3536 powders with flowability is greater than 46 μm, which cannot meet the demand for 3D printing (15-53 μm). The flowability of GH3536 powder can be restored by adding zinc stearate lubricant. After lubricant modification, the printed samples display a 16% increase in elongation, along with a little improvement in tensile strength. This paper also investigates the flow properties change of raw powder heated at 100°C, 200°C, 300°C, and 400°C. When the temperature rises beyond 400°C, powder flowability fully returns, along with oxygen content increasing. Overall, the lubricant modification technique is appropriate in actual manufacturing, but the flow rate value of powders is typically high, exceeding 70 s/50 g. Increasing particle size and heat treatment can improve powder flowability and the flow rate of powder is less than 20 s/50 g.