Mechanical and electrical properties of selective laser‐melted parts produced from surface‐oxidized copper powder

Abstract

Selective laser melting of pure copper is challenging because of its high optical reflectivity and thermal conductivity. Accordingly, the surface of pure copper powder was modified by oxidation to enhance the optical absorption. The powder with improved optical absorption facilitated the production of crack‐free and dense copper parts at relatively lower laser energy density in both argon and nitrogen atmosphere. The microstructural analysis demonstrated the presence of stable melt tracks without obvious porosity. A very high electrical conductivity of approximately 89% of the international annealed copper standard, the hardness of approximately 93 HV, a tensile strength of approximately 270 MPa, and ductility of approximately 28% were achieved in the as‐built condition.

Laser Powder Bed Fusion of Metal Coated Copper Powders

“…Recently, the L-PBF processability of copper has been increased by coating the surface of the powder with materials with a higher absorptivity. This has been achieved by oxidizing the copper surface [22], yielding decreased porosity, which agrees with similar results on 18 K gold alloys [23]. Mixing of copper powder with carbon nanoparticles has also been attempted [24], but did not have a significant effect on the porosity.…”

Influence of Carbon Nanoparticle Addition (and Impurities) on Selective Laser Melting of Pure Copper

“…Oxygen, on the other hand, has an extremely low solid-solubility (up to 2 ppm) in copper [47]. Therefore, its potential negative influence on the electrical conductivity of copper is negligible, when compared to phosphorus [26].…”

“…Accordingly, they could fabricate dense parts from Cu-Cr [17,18,19], Cu-Cr-Zr [20,21,22], Cu-Sn [23,24], and Cu-Zn [25] alloys. However, the thermal and electrical conductivity values of these parts are substantially lower when compared to pure copper parts in the as-built condition [8,26]. Moreover, an upcoming trend to fabricate copper parts by SLM with high thermal and electrical conductivity, is to coat or convert the outer surface of the virgin copper particles with/into a thin (<100 nm) surface layer with higher laser absorption [26], Therefore, the current paper proposes coating copper powder with carbon nanoparticles.…”

“…However, the thermal and electrical conductivity values of these parts are substantially lower when compared to pure copper parts in the as-built condition [8,26]. Moreover, an upcoming trend to fabricate copper parts by SLM with high thermal and electrical conductivity, is to coat or convert the outer surface of the virgin copper particles with/into a thin (<100 nm) surface layer with higher laser absorption [26], Therefore, the current paper proposes coating copper powder with carbon nanoparticles. Although the idea of coating the copper powder with carbon has been proposed before [27], no one yet reported on their SLM behavior or on the obtained mechanical and electrical properties.…”

Surface Modified Copper Alloy Powder for Reliable Laser-based Additive Manufacturing

“…Within such developments, multiple attempts have been undertaken to fabricate dense copper parts using commercially available fiber lasers with output power values up to 400 W. However, the available laser power was not sufficient to melt the powder particles resulting in low-density copper parts with lack-of-fusion defects [4,[8][9][10]. Accordingly, few researchers utilized a high-power 1 kW laser with a focused beam-diameter below 100 µm [6,[11][12][13]. The use of high laser power of 600-800 W, in combination with a low scanning speed (200-400 mm/s), resulted in the fabrication of nearly dense (96-99%) copper parts [6,12,14].…”