Enhancing copper processability via carbon nanotubes reinforcement in Powder Bed Fusion - Laser Based. Dragon Copper

Powder Bed Fusion - Laser Based (PBF-LB) is a widely used additive manufacturing technology for metallic materials, but its application to pure copper remains challenging due to its high reflectivity in the near-infrared (NIR) wavelength range, commonly employed in commercial laser systems. This paper proposes a strategy to overcome this limitation by incorporating carbon nanotubes (CNTs) into the powder bed, enabling the PBF-LB manufacturing of pure copper while simultaneously enhancing its functional properties, as demonstrated through multiscale characterization performed at both powder and manufactured level. The work led to the development of a nanocomposite material, patented by the National Institute for Nuclear Physics (INFN) and Sapienza University of Rome, known as Dragon Copper, consisting of a pure copper matrix reinforced with CNTs. NIR spectroscopy revealed that the addition of a small amount of CNTs (0.1 wt%) into the copper powder efficiently reduces its reflectivity across all investigated wavelengths, including 1064 nm, the operating wavelength of the PBF-LB laser employed in this study. Thanks to the role of CNTs as efficient laser absorbers, Dragon Copper showed higher densification, enhanced microstructural stability and significant improvements in both tensile strength and ductility compared to pure copper, as confirmed by SEM analysis and tensile tests. Raman spectroscopy demonstrated the preservation of CNTs structural integrity after the PBF-LB process, suggesting their active contribution in mechanical reinforcement. Although moderate reductions in thermal and electrical conductivities, the overall performance of Dragon Copper demonstrates the potential of this approach for advancing PBF-LB manufacturing of high-performance copper components.