Tribological Study of Beeswax-Thickened Biogrease and Its Modification with Carbon Nanoparticles

Possibility to produce the biogrease using rapeseed oil as a base oil, beeswax as a thickener and its modification with functional anti-wear and antioxidant additives and carbon nanoparticles of graphene oxide and thermally expanded graphite nanoparticles were evaluated. Tribological tests were performed using a four-ball tribo-tester and the rheological characterization using a cone-plate Brookfield rheometer. The rheological parameters were correlated with the physico-chemical properties of the greases. The resulting variation of the rheological parameters with the temperature exhibits non-Newtonian behavior. Although the increasing proportion of beeswax worsens the tribological properties of investigated grease, the functional additives and nanoparticles significantly improve the thermal properties of the lubricant, yield stress, viscosity and tribological properties reducing the wear rate.