Low-temperature pre-oxidation of copper powder for enhanced infrared laser absorptance

The widespread application of copper additive manufacturing (AM) via laser is hindered by complex interactions between powder properties and energy sources. The optical response of copper powder is strongly influenced by its surface condition, making surface modification a promising approach to tailoring its laser absorptance. In this study, low-temperature oxidation in the range of100–200°C was employed to modify the powder surface and enhance laser absorptance. This work establishes the relationship between powder absorptance and oxidation behaviour of copper. The pre-oxidation treatment formed a thin cuprous oxide layer on the copper particle surfaces.Phase and surface morphology analyses were performed to clarify the oxidation behaviour of copper powder in the low-temperature range. After pre-oxidation at 150 °C for 300 min, the reflectivity at 1068 nm decreased from 53.1% for the as-received powder to 29.7%, while. the equivalent oxide layer thickness was estimated to be 343 nm based on UV–NIR spectroscopy and an optical oxide-layer model. . This study provides a promising route for controlling the oxidation state of copper powder to tailor its optical response, with potential applications for laser based additive manufacturing of copper.