Tribological performance of few layer graphene on textured M2 steel surfaces

• Laser ablated microgrooves can replenish graphene during the wear process.
• 35% is the optimum area density to improve the tribological performance of graphene.
• Low COF (~ 0.22) can be sustained for 870 sliding cycles.

In this study, we propose an easy and effective way to enhance the tribological performance of few layer graphene on M2 steel surfaces. Microgrooves with different area ratios were fabricated on M2 steel surfaces by laser surface texturing method. Subsequently, few layer graphene flakes were dripped on the textured surfaces with graphene-containing ethanol solution. The macro-scale tribological performance of graphene was investigated by ball-on-disk tribometer. The results showed that graphene lubrication with appropriate groove area ratios (35% and 56%) were effective in enhancing the wear resistance compared with that of the bare M2 steel, the improvement was attributed to the effectiveness of wear debris entrapment and the formation of protective carbon layer. Especially with 35% groove area, there was sufficient graphene to reduce the friction, meanwhile, enough support to the high contact stress can be provided as well, demonstrating an obvious improvement in the friction behavior. As a result, low coefficient of friction (COF) around 0.22 can be sustained for 870 sliding cycles.