In-situ surface modified water-soluble Cu nanoparticles as lubrication additives in water-based cutting fluids

Water-based lubricants are essential in the field of tribology , and the application of nanoparticles as additives in water-based lubricants shows promise and significant practical importance. In this study, water-soluble Cu nanoparticles modified with methoxypolyethyleneglycol xanthate long-chain polymers were fabricated by a in-situ surface modification method. The tribological behavior of the Cu nanoparticles synthesized as additives in a water-PEG system was evaluated using a universal micro-tribotester. It was found that the synthesized nanoparticles could be stably dispersed in the water-PEG system and could enhance the tribological properties and load-carrying capacity of the system significantly. For example, the coefficient of friction could be reduced to 0.052, and the P B value increased to 588 N when the Cu nanoparticles were added at a mass fraction of 1.5 %. This was mainly attributed to the formation of a boundary lubrication film consisting of Cu, Fe 2 O 3 , Fe 2 (SO 4 ) 3 , and FeS throughout the entire friction process. The boundary film effectively prevents direct contact between the friction surfaces, thereby improving the tribological properties. The incorporation of Cu nanoparticles as additives into commercial cutting fluids resulted in a lower coefficient of friction and significantly enhanced the extreme pressure performance of the cutting fluids, demonstrating promising application prospects.