Synergistic Study of Solid Lubricant Nano-Additives Incorporated in canola oil for Enhancing Energy Efficiency and Sustainability

Abstract

In recent years, with the development of eco-friendly lubricants, different vegetable oils have been studied and found to improve the overall tribological performance compared to petroleum-based oils. Being one of the commonly used vegetable oils, canola oil has become popular due to its non-toxicity and low cost. However, this bio-lubricant lacks tribological performance compared to petroleum-based oils. To improve its performance, sustainable solid additives such as graphene nanoplatelet (GNP) and hexagonal boron nitride (hBN) have recently gained the researcher’s attention. While incorporating nanomaterials in the oil as additives is a promising way to improve base oil’s performance, the excessive use of nanoparticles can introduce undesirable effects. This study investigated canola oil’s tribological performances with the addition of 0.5, 1.0, 1.5, and 2.0 wt.% GNP and 0.5, 1.0, and 1.5 wt.% hBN nanoparticles. The dynamic viscosities of these seven settings showed higher viscosity for GNP-incorporated oils compared to that with hBN. The boundary lubrication regime was targeted for the coefficient of friction (COF) and wear analyses during each pin on the disk test. It was observed that for the GNP, 1.5 wt.% provided the minimum COF (52% less than base oil), whereas, for the hBN, 1.0 wt.% provided the lowest (40% less than base oil) values. Based on these insights, three nano lubricant mixtures were formulated by incorporating both GNP and hBN settings in different ratios. These mixtures provided an optimum positive synergy by reducing 56% friction and 90% wear compared to the base oil. These percentage values were significantly more compared to both GNP and hBN based lubricants in their individual settings. These improvements in the mixture were due to a composite film formed which protected the interacting surfaces and also due to the polishing mechanisms. Therefore, incorporating both these nanoparticles in canola oil could reduce friction and wear and thus help in better energy conservation.