Preparation, characterization, and tribological properties of oleic diethanolamide-capped zinc borate-coated graphene oxide composites

In this paper, a simple facile route for preparing zinc borate (ZB)/graphene oxide (GO) composites (ZB/GO) through a liquid phase-based ultrasonic-assisted stripping approach was demonstrated. As revealed by the FT-IR, XRD, Raman, UV-vis, TEM and SEM techniques, ZB hybrids were successfully composited with GO sheets. In order to highly disperse the composites into the base oil, the composites would be chemically modified in a reflux reaction with oleic diethanolamide (OD), i.e. OD-ZB/GO. The tribological properties of OD-ZB/GO as an additive in the base oil were tested by the four-ball wear machine. The results showed that the friction coefficient (COF) and the wear scar diameter (WSD) of the OD-ZB/GO-based oil (2.0 wt% of ZB/GO) were about 48.2% and 40.0% decline than those of the 500 SN base oil. Moreover, it could be found that the OD-ZB/GO-based oil showed a good carrying capacity at higher applied loads and an obviously reducing oil temperature performance in comparison of GO sheets and ZB hybrids. For proposing the wear mechanism, the as-prepared OD-ZB/GO in different viscosity base oil also was investigated intensively. The Raman spectra of wear surface revealed that the OD-ZB/GO materials entered the interfaces of motorial frictional pairs relied on base oil, thus displaying its antifriction and antiwear ability.