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 °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 (μ = 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.