Eco-Friendly Trinickel Disulfide Nanoparticles Advancing Poly-α-olefin Lubrication

Friction and wear remain formidable challenges for mechanical components in modern industrial applications. Traditional lubricants rely on a combination of additives that synergistically enhance performance but often undergo thermal degradation at increased temperatures, causing mechanical lubrication failure. Trinickel disulfide (Ni3S2) nanoparticles have emerged as promising candidates owing to their excellent tribological properties, chemical stability, and resilience at high temperatures. Compared with nonmagnetic nanoparticles, the magnetic properties of Ni3S2 nanoparticles can quickly form a protective film on the metal surface and reduce mechanical damage. Nevertheless, the conventional synthesis route of Ni3S2 requires high-temperature conditions and the release of toxic gases, resulting in environmental pollution. To address these limitations, we synthesized oleylamine-modified magnetic Ni3S2 nanoparticles (OA-Ni3S2 NPs) through a liquid-phase approach under mild conditions. Transmission electron microscopy (TEM) analysis indicated that OA-Ni3S2 NPs had an average particle size of ∼40 nm. Tribological evaluation in poly-α-olefin-6 (PAO6) base oil, conducted using a four-ball tribometer, revealed that OA-Ni3S2 NPs reduced the coefficient of friction (COF) by 31% and wear scar diameter (WSD) by 40% compared to pristine PAO6, underscoring their exceptional friction-reducing and antiwear performance, while mechanistic studies further clarified the sliding behavior of the nanoparticles at the friction interface. These findings underscore the potential of OA-Ni3S2 NPs as sustainable lubricant additives and provide a promising foundation for their deployment in high-temperature industrial systems.