Ball Milled Graphene Nano Additives for Enhancing Sliding Contact in Vegetable Oil.

Emad Omrani,Afsaneh Dorri Moghadam,Arpith Siddaiah,Pradeep L Menezes,Pradeep Rohatgi,Uma Garg

doi:10.3390/nano11030610

Emad Omrani, Afsaneh Dorri Moghadam + Show 4 more

Open Access

https://doi.org/10.3390/nano11030610

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Abstract

Graphite nanoplatelets (GNPs) as an oil nano additive has gained importance to enhance the lubrication properties of renewable lubricants, such as vegetable oils. Using appropriately processed GNPs is necessary to gain the required tribological advantage. The present study investigated ball-milled GNPs, to understand the effect of GNPs concentration, and applied load on tribological behavior. Pin-on-disk tests were employed, to investigate the tribological performance of the nano-additive oil-based lubricant in the boundary lubrication regime. In order gain an understanding of the lubrication mechanism, Scanning Electron Microscope (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), and Raman Spectroscopy were performed for characterization. The study found that there is a critical concentration of GNPs, below and above which a reduced wear rate is not sustained. It is found that the tribological enhancements at the optimum concentration of GNP in boundary lubrication condition are a result of reduced direct metal–metal contact area at the interface. This phenomenon, along with the reduced shear strength of the ball-milled GNPs, is indicated to reduce the formation of asperity junctions at the interface and enhance tribological properties of the nano-additive oil-based lubricant.

Highlights

Despite the environmental advantages to using pure natural oils, especially canola oil, they do suffer poor oxidative stability, which is substantially determined by the nature of the base oils [4]. They are susceptible to oxidative degradation due to the presence of free fatty acids and the presence of double bonds in the carbon chain. These shortcomings of canola oils have led to studies looking at enhancing their tribological performance by the use of nano additives [5,6] in addition to chemically modifying them to be usable as mixed lubricant additives in petroleum-based oils [7,8]
Graphite nanoplatelets (GNPs) were used as nano additives in canola oil
The shear force applied on a few layers of graphene between contact surfaces can cause the exfoliation of GNPs [33,34], thereby it can contribute to the lubrication behavior of the base oil

Summary

Introduction

Despite the environmental advantages to using pure natural oils, especially canola oil, they do suffer poor oxidative stability, which is substantially determined by the nature of the base oils [4]. They are susceptible to oxidative degradation due to the presence of free fatty acids and the presence of double bonds in the carbon chain. These shortcomings of canola oils have led to studies looking at enhancing their tribological performance by the use of nano additives [5,6] in addition to chemically modifying them to be usable as mixed lubricant additives in petroleum-based oils [7,8]

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