The effect of surface roughness on the tribological performance of environmentally friendly bio-based lubricants with varying particle size

Environmentally friendly bio-based lubricants are gaining attention within the lubrication industry as an alternative to petroleum-based lubricants. In the present investigation, a pin-on-disk apparatus was used to study the effect of surface roughness on the tribological performance of bio-based lubricants containing particulate additives. In the experiments, copper pins were slid against aluminum disks of different surface roughnesses in the presence of canola oil containing nano-, submicron-, and micron-sized hexagonal boron nitride particulate additive lubricant at the interface. Results showed that the tribological performance of bio-based lubricants is influenced by the surface roughness of the counter materials and the particle size. More specifically, for rough surfaces, the friction and wear performance increases when larger particles are used in the lubricants. For the smooth surfaces, the friction and wear performance increases when smaller particles are used in the lubricants. The influence of roughness and particle size on the tribological performance is attributed to the load carrying ability and formation of protective layer of the particles at the interface.