Analyses of Tribological Properties of Castor Oil With Various Carbonaceous Micro- and Nano-Friction Modifiers

The present work investigates the tribological properties of castor oil with various carbonaceous friction modifiers (nano and microsize additives) assessed using four-ball tester as per ASTM D 4172 and ASTM D 2783. Castor oil has been chosen because of its high viscosity and ease of availability. Graphite, multiwalled carbon nanotube (MWCNT), and multilayered graphene are used as friction modifiers (FMs) in castor oil on weight percentage basis. Significant enhancements of tribological properties with a certain level of concentration of friction modifiers have been observed. The surface features of the tested balls were analyzed using a three-dimensional noncontact type profilometer, scanning electron microscope (SEM), and energy dispersive system (EDS). Decrease in surface roughness indicated better antiwear properties in case of nanofriction modifiers-based castor oil as compared to micrographite-based and neat castor oil (NCO). In order to assess the suitability of castor oil as a replacement for mineral oil, the results of castor oil samples are also compared with commercially available mineral oil. The tribological properties of castor oil are found to be competitive and generally superior to the mineral gear oil. The data generated are used to develop a neural network model to map the input-output correlation.