Synthesis and tribological characterization of stable dispersions of thermally reduced graphite oxide

Novel dispersions of thermally reduced graphite oxide (TRGO) in ester oil were prepared by means of high-pressure homogenization. Due to the versatility of the homogenization process, TRGO dispersions with a wide concentration range of 0.01-0.5 wt% could be prepared both in ester oil that contains additives (FGL46 E) and in an additive-free ester oil formulation. The obtained dispersions were characterized with respect to their sedimentation stability and their tribological properties. Therefore, highly resolved Stribeck curves were measured in the boundary region. Compared to benchmark dispersions of carbon black and graphite, our TRGO-containing formulations showed considerably lower friction and wear. The results of this study show the positive influence of TRGO on the friction behavior of ester oil formulations, thereby presenting TRGO-containing ester oils as a promising new family of liquid-based lubricants.