Rheological and tribological properties of rice bran oil grease (RBOG) with h-BN nanoparticles - An experimental study

Vegetable oil-based semi-solid lubricants are preferred in applications where environmental pollution is a major concern (soil or water pollution). The motive of the current study is to formulate and assess the rheological and tribological behavior of rice bran oil lithium-based bio-grease. The effect of various concentrations of thickener (lithium stearate) and hexagonal boron nitride nanoparticles on rheological properties of RBOG is studied. The thickener is added in a concentration of 4 wt. %, 10 wt. %, and 16 wt. %. The hexagonal boron nitride nanoparticles are added in a concentration of 1 wt. %, 2 wt. %, and 3 wt. %. The rheological properties studied are viscosity, shear stress, storage modulus, loss modulus, and yield stress. Anton Paar Rheometer MCR-102 is used to evaluate the rheology of the grease. The experimental results reveal that the RBOG without nanoparticles depict the maximum COF whereas, RBOG + 3 wt. % h-BN depict the minimum COF. Further, the addition of h-BN nanoparticles in RBOG has reduced the wear scar diameter from 0.93mm to 0.67mm.