Novel top-down kg-scale processing of 2D multi-layered graphene powder and its application as excellent lubricating additives in commercial engine oils

Multi-layered graphene (MLG) powder is prepared on a kg-scale using a novel fluid-assisted processing of exfoliated graphite. Each MLG particle is a few μm laterally and is constituted by a few graphene layers. When MLG-dispersed commercial engine oil was used as a lubricant, the tribological properties (i.e., friction and resistance to wear) of the contacting metal surfaces were significantly enhanced. The average coefficient of friction (CoF) at room temperature and 75 °C was reduced by ~25.5 % and ~ 16 %, respectively, while the wear resistance at room temperature and 75 °C was improved by ~13 % and ~ 16 %, respectively. MLG-dispersed engine oil forms a protective tribo-film adhering to the contacting metal surfaces, resulting in ultra-low interface friction. The MLG-dispersed engine oil (acting as a tribo-film) diminishes the effective direct metal-to-metal contact area, minimizing the wear.