Study on the effects of graphene oxide for tribological properties and cooling in lubricating oil

To evaluate the potential lubricating properties of graphene oxide (GO) as an oil additive, the tribological behaviors of Si₃N₄/GCr15 sliding pairs lubricated with Mobil DTE oil light (MDOL) containing different GO concentrations (0–0.3 wt%) were investigated with a ball-on-disc tribometer. The wear scar widths (WSWs) of the GCr15 discs were characterized via digital 3D microscopy. Scanning electron microscopy, energy-dispersive x-ray spectroscopy, and Raman spectroscopy were employed to investigate the lubricating mechanism of the base oil containing the GO additive. The frictional properties of the Si₃N₄/GCr15 sliding pairs were significantly improved after adding GO into the base lubricating oil, and a good cooling effect was observed. For MDOL containing 0.15 wt% GO at a rotational speed of 2500 r · min⁻¹ and 80 N load, the average friction coefficient (AFC) was reduced by 67.37%. For MDOL containing 0.15 wt% GO at a rotational speed of 2000 r · min⁻¹ and 80 N load, the temperature rise (TR) and WSW were decreased by 39.86% and 28.37%, respectively. The lubrication mechanism was studied to explain the improvements in the AFC and WSW, which were attributed to the formation of a protective deposited film. The decrease in the TR for the Si₃N₄/GCr15 sliding pairs was ascribed to the high thermal conductivity and large specific surface area of the GO additive. (paper)