Tribological Behaviour of Graphene Coating Deposited Using Electrophoretic Process Under Dry Sliding Conditions

This study examined the friction and wear performance of graphene-coated steel in comparison with an uncoated steel/steel contact under controlled reciprocating sliding. Tribological experiments were carried out at normal loads of 2.5 N and 7.5 N over a sliding time of 1200 s using a sliding speed of 0.1 m/s and a stroke length of 5 mm. Under these conditions, the graphene coating lowered the steady-state coefficient of friction by more than 80% under both loads and significantly reduced the wear rate by ~22% and ~ 50% with 2.5 N and 7.5 N, respectively, compared with the bare steel pair. The uncoated steel contact showed a clear running-in stage followed by high friction, whereas the graphene-coated surface significantly reduced the running-in time and achieved a stable low-friction state. These results indicate that graphene effectively forms a stable, low-shear interfacial layer that significantly removes direct metal-to-metal contact, suppresses wear, and promotes stable sliding. After testing, the wear tracks were examined using optical microscopy and 3D surface profilometry