Tribological Performance of Cu-rGO-MoS2 Nanocomposites Under Dry Sliding

Nanostructured MoS2 grown on reduced graphene oxide (rGO-MoS2) is demonstrated as a lubricating reinforcement material for copper matrix composite. The Cu-rGO-MoS2 nanocomposites having variable dosages of rGO-MoS2 (0.5 to 2.0 wt%) are prepared via a combinational approach of powder metallurgy and then spark plasma sintering at 700 degrees C. The XRD and Raman analyses suggested the preparation of rGO-MoS2 hybrid, whereas HRTEM images revealed the thorough distribution of MoS2 nanosheets over the rGO. The tribological properties of Cu-rGO-MoS2 nanocomposites were evaluated against the EN 31 steel ball under the variable loads (4-10 N). The coefficient of friction was found to decrease with increasing of rGO-MoS2 content. The Cu-rGO-MoS2 nanocomposite with a 2.0 wt% of rGO-MoS2 hybrid exhibited the lowest and stable coefficient of friction (mu =0.2) among all the nanocomposites. The high mechanical strength and low shearing properties driven by the lamellar structure of rGO-MoS2 furnished the self-lubricating properties to Cu-rGO-MoS2 nanocomposites. A combination of adhesion, oxidation, abrasion, and delamination of materials are revealed as major events for the wear mechanisms. These wear events are governed by the dosage of rGO-MoS2 reinforcement in the Cu-rGO-MoS2 nanocomposites and applied load. The results indicate that rGO-MoS2 has the potential to be used as a solid lubricant in the metal matrix composites.