N-Heterocyclic Carbene Deposition on a Copper Powder Surface Using Mechanochemistry

Metal powders are crucial precursors for manufacturing surfaces through thermal spraying, cold spraying, and 3D printing methods. However, surface oxidation of these precursors poses a challenge to the coherence of the metallic materials during manufacturing processes. Herein, we introduce a method for surface modification of copper powder with N-heterocyclic carbenes (NHCs) using mechanochemistry to mitigate surface oxidation. A resonant acoustic mixer was used to deposit five different carbenes on copper powders using benzimidazolium hydrogen carbonate precursors and a trace amount of solvent. Significant oxide reduction was observed by X-ray photoelectron spectroscopy (XPS), and the immobilization of NHCs on the powder was confirmed by mass spectrometry and XPS. The consistent morphology of the modified copper powder minimizes any potential impact on subsequent manufacturing processes. Moreover, a life cycle assessment indicates the potential environmental hotspots, leading to recommendations to develop lower-footprint processes. Overall, the mechanochemical method to produce NHC-modified metal powders with a higher metallic content provides great prospects for powder precursors to produce coatings from thermal spray, cold spray, and additive manufacturing processes.