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

Soumya Sikdar,Md Hafizur Rahman,Pradeep L Menezes

doi:10.3390/su14010290

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.

Highlights

Bio-based oils obtained from vegetables have been used as lubricants for minimizing friction and wear from ancient times [1,2]
In an attempt to minimize the use of petroleum-based lubricants owing to concerns of environmental protection, increase in price, and depletion of crude oil reserves, there has been an increase in research pertaining to natural oils [5,6]
Studies have shown that compared to synthetic oils, bio-based oils from vegetables possess lower volatility, higher lubricity, higher load-carrying potential, higher viscosity index, and higher shear stability [1,7]

Summary

Introduction

Bio-based oils obtained from vegetables have been used as lubricants for minimizing friction and wear from ancient times [1,2]. Studies have shown that compared to synthetic oils, bio-based oils from vegetables possess lower volatility, higher lubricity, higher load-carrying potential, higher viscosity index, and higher shear stability [1,7]. They can be a suitable alternative to petroleum-based oils. One of the main reasons nowadays for inclination towards bio-based oils is due to their constitution of triacylglycerol and long chains of polar fatty acids [8].

Methods

Results

Conclusion