Evaluation of boron nitride particles on the tribological performance of avocado and canola oil for energy conservation and sustainability

In the present investigation, experiments were conducted using a pin-on-disk apparatus to study the tribological performance of environmentally friendly multi-phase lubricants consisting of natural plant-based liquid lubricants and hexagonal boron nitride (hBN) solid additives. Among the natural plant-based liquid lubricants, a high oleic acid lubricant, such as avocado oil, showed the best tribological performance when compared to other natural plant-based lubricants, which further demonstrated the importance of appropriate natural oil selection for tribological applications. In order to develop an optimal multi-phase lubricant, hBN particles with varying sizes were incorporated as additives in the avocado oil. Experiments revealed that particle additive size with regards to initial surface roughness affects the tribological performance of the multi-phase lubricant. It was found that this multi-phase lubricant with nano-sized additives showed the best performance when compared to multi-phase lubricants with micron-sized and submicron-sized additives. More specifically, the lubricant mixtures had friction reductions from 8 to 64 % for particles ranging from micron-sized to nano-sized, respectively. The wear also decreased in the lubricant mixtures with reductions from 13 to 70 % for particles ranging from micron-sized to nano-sized, respectively. These mechanisms for enhanced tribological performance are discussed in this investigation.