N-Heterocyclic carbene-promoted copper powder conditioning for thermal spray applications

Abstract

Copper powder is essential in the thermal spray industry for its excellent thermal and electrical conductivity. However, uncontrolled surface oxide on Cu powder degrades coating performance by weakening inter-particle bonding. This study introduces a novel method using N-heterocyclic carbene (NHC) chemistry to remove surface oxides from Cu powder via a one-pot immersion process. NHC functionalization not only eliminates surface oxides but also acts as a capping agent, enhancing the corrosion resistance of the sprayed coatings. Detailed investigations using scanning electron microscopy, X-ray photoelectron spectroscopy, and laser desorption/ionization spectroscopy confirmed the successful NHC treatment. The process was scaled up from gram to kilogram scale, demonstrating its industrial feasibility. Mechanical and corrosion tests show that NHC-treated Cu powder thermal sprayed coatings have superior inter-particle bonding compared to those from untreated-Cu powder. This approach shows great promise for improving the quality of metal powder coatings by effectively removing surface oxides.