| The friction and wear properties of ultrathin films of graphene, graphene oxide (GO) and reduced GO at nanoscale were investigated using friction force microscopy (FFM). Graphene and GO were found to reduce friction for sliding between a Si AFM tip and SiO2 surfaces by ~6 and ~2 times respectively. As a solid lubricant, GO was found to wear under small normal load, while graphene was found to be highly wear resistant. The higher propensity for wear of GO as compared to graphene may limit its usefulness as coatings for micro/nano-electro-mechanical systems (M/NEMS) with high contact stress applications. Adhesion of GO has been found to increase with elevated relative humidity. Effect of chemical structure on the friction and wear properties of GO was then investigated to overcome the challenge for GO as a solid lubricant. It was found that reduced GO exhibited higher anti-wear properties than GO and proves to be effective in designing coatings for M/NEMS with tunable properties. |
