Mono-dispersed Ag/Graphene nanocomposite as lubricant additive to reduce friction and wear

The unique structure and excellent mechanical property endow silver/graphene nanocomposite with great potential in many lubrication fields. However, its easy aggregation, poor dispersibility and complex synthesis procedures have long been a headache. Herein, we report a simple and effective one-step laser irradiation strategy to fabricate a silver/graphene nanocomposite, which effectively avoids the aggregation and enjoys a good dispersion stability. Structural investigation confirms that mono-dispersed silver (Ag) nanospheres evenly grow on the layered graphene sheets, and this regularly laminated structure further guarantee enhanced lubricating effect. Tribological experiments demonstrate that 0.1 wt% addition of this composite could readily reduce the friction coefficient and wear spot diameter by 40% and 36%, respectively. Detailed lubricating mechanism experiments demonstrate that self-lubrication induced by such layered structure, the change from sliding friction to rolling friction, and the self-repair effect due to Ag nanospheres synergistically contribute to the excellent lubricating performance. More importantly, in comparison with commercial lubricant additives, such Ag/graphene nanocomposites exhibit better lubricating effect and contain no metal corrosion and environmental pollution elements. This study demonstrates that laser irradiation is a powerful strategy to prepare unique layered composite materials for promising lubricant additive to reduce friction and wear.