Effect of pulsed and continuous arcs on copper powders prepared by arc micro explosion machining

A new copper powder preparing method is proposed, which can flexibly manufacture spherical copper powders by arc micro explosion machining. The effects of pulsed arc and continuous arc on copper powders prepared by arc micro explosion machining were investigated. The properties and microstructure of the two types of copper powders were analyzed using high-resolution synchrotron X-ray computed tomography (CT), scanning electron microscopy(SEM), and Transmission electron microscope(TEM). The results showed that under the same conditions, the type of arc has an effect on the size, surface finish and crystal structure of copper powder. In contrast, it has no significant effect on the size distribution, sphericity, purity and oxygen content. Under the condition of voltage 100V and current 400A, the D50 of copper powder prepared by pulsed arc is 63.08μm, and the D50 of copper powder prepared by continuous arc is 72.24μm; the copper powder made by continuous arc has higher surface finish than that made by pulsed arc; the polycrystalline structure is easy to be obtained by the copper powder prepared by pulsed arc, while monocrystalline structure is easy to be obtained by continuous arc. The two copper powders had the advantages of narrow particle size distribution, good fluidity, high sphericity, high purity, low oxygen content and non-satellite powder, which met the requirements for copper powders in additive manufacturing (AM). This research result can serve as a basis for selecting the arc type for arc micro explosion machining of copper powders.