Tribological application study of biomass-derived carbon microspheres in multi-matrix lubricants

Eco-friendly lubricant additives play a pivotal role in saving energy and advancing sustainable development. Focusing on the tribological properties of biomass-derived carbon microspheres (CSs), this study successfully synthesized by a one-step glucose hydrothermal method and systematically evaluated as lubricant additives in water-based polyethylene glycol (PEG400), non-polar polyalphaolefin base oil (PAO6), and commercial full synthetic motor oil (0 W-20). Results demonstrate that CSs exhibit excellent dispersion stability and significant friction-reduction and anti-wear effects in all three lubricants. Specifically, CSs maintained colloidal stability for 180 days in PEG400, achieved a maximum 32.7 % friction coefficient reduction in 0 W-20, and a maximum wear volume decrease of 65.6 % in PAO6. Analysis indicates that the excellent lubrication performance is mainly ascribed to the enhanced interfacial adhesion force derived from improved wettability, which contributes to the rapid formation of homogeneous adsorption oil films at the sliding interface. Simultaneously, the nanobearing effect generated by the spherical structure of CSs and the friction-induced formation of Fe₃O₄/CS composite films synergistically interact to achieve high-efficiency lubrication. This study systematically evaluates the application potential of CSs in both polar and non-polar lubricant systems, providing valuable insights for the future development of high-performance lubricants.