Investigating the lubrication performance of vegetable oils reinforced with HNT and MMT nanoclays as green lubricant additives

Currently, technology demands a sustainable and more environmentally friendly lubricant. In addition, government regulations and recent concern about using petroleum-based lubricants have increased research on environmentally friendly lubricants such as vegetable oils. This study investigates the lubrication performance of corn and peanut oils reinforced with different concentrations of Halloysite clay nanotubes (HNTs) and Montmorillonite nanoclay (MMT) as green lubricant additives. Block-on-ring wear tests following the ASTM G-077-17 standard procedure were conducted to investigate the effect of different nanoparticle (NP) concentrations on the coefficient of friction (COF) and wear volume loss. Different surface analytical methods, including scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and profilometry, were used to analyze the worn surfaces. Additionally, the lubrication performance of the newly developed vegetable oil-based nanolubricants was evaluated in an industrial-type application through tapping torque tests. The tribological results revealed that the coefficient of friction (COF) for the corn oil was lowered by 56% and 77% with the addition of HNT and MMT NPs, respectively, compared to corn oil without additives. Similarly, the COF for the peanut oil was lowered by 66% and 81% with the addition of HNT and MMT NPs, respectively, compared to peanut oil without additives. Moreover, the volumetric wear decreased by 78% and 75% for the corn oil and 67% and 62% for the peanut oil when using HNT and MMT NPs as lubricant additives, respectively. Therefore, based on the experimental results, the authors conclude that vegetable oils reinforced with HNT and MMT nanoclays have the potential to be used as good biodegradable nanolubricants.