Laser powder bed fusion (LPBF) fabrication of copper adds significant value to high-performance applications, particularly in cases where complex geometries and high conductivity are required, such as heat sinks or antennas [1]. However, the LPBF fabrication of copper is currently limited by the low near-infrared absorption and high thermal conductivity of copper, resulting in suboptimal quality of the formed parts. Modifying copper powders with higher absorption material is a practical and cost-efficient solution to compensate the insufficient energy for melting, which offers great advantages over upgrading the equipment to higher power or short-wavelength laser equipment [2]. The ongoing research about modifying copper powder for LPBF primarily focuses on alloying or mixing with other additives to improve its density and resulting properties [3]. The impact of these modifications on the absorption and melt pool behaviours during the LPBF process is still not fully understood.

In this study, a mussel-inspired nanocoating was applied to copper powders with the goal of improving their absorption through the creation of a uniform and full-coverage nanoscale layer. The effects of the nanocoating on the melt pool morphology and laser absorption were investigated. To accurately measure the offline absorption and in-situ absorption, a custom absorption system was developed for this study. The absorption results from both tests showed an increase in absorption rates after the nanocoating was applied to copper powders. These findings demonstrate the effectiveness of this nanocoating strategy for improved energy efficiency during LPBF process; in other words, it can further enhance the productivity by increasing processing speed. Inert gas fusion and optical emission spectroscopy are used to measure the nanocoating-induced impurities and evaluate the coating constituents that have vaporised during the laser-material interaction. Therefore, this nanocoating strategy, which potentially provides a transient absorbent, holds promise for achieving a balance between improved energy absorption and minimal induced impurity.

This effective fabrication of copper also provides valuable insights for the LPBF fabrication of other highly reflective metals, such as silver or gold. The range of applicable materials for LPBF is expected to expand in the future, offering greater versatility and flexibility in the production of high-quality metal components.