Friction Properties of Graphene Coating Prepared by Electrophoretic Deposition

The present study reports the significantly enhanced tribological performance of the silicon wafer by utilizing the graphene coating on its surface as a solid lubricant. Graphene coatings with different surface morphologies and microstructures were deposited by electrophoretic deposition (EPD) method by adopting different applied voltages, and then their friction reducing effect as the solid lubricant was investigated in a set of ball-on-plate reciprocating friction tests (1~9 N). Moreover, the surface morphology, microstructure and composition of graphene coating were examined by scanning electron microscope, energy dispersive spectrometer, optical microscope, Raman and X-ray photoelectron spectroscopy. The results show that the coefficients of friction of graphene coated silicon wafer arrived at a steady-state around 0.1, reduced by over 80% compared with that of the bare silicon, which was about 0.6. Compared with increasing the EPD voltage, elongating the deposition duration at low voltages (15~60 V) in the EPD process, which produced graphene coatings with more compact microstructure, proved to be an effective approach to enhance the load-bearing capacity of the graphene coating as a solid lubricant.