Lubrication Performance of Sunflower Oil Reinforced with Halloysite Clay Nanotubes (HNT) as Lubricant Additives

Abstract

This study evaluates the tribological performance of nanolubricants of a vegetable oil (sunflower oil) reinforced with different concentrations of environmentally-friendly nanoparticles of halloysite clay nanotubes (HNTs). Tribological characterization was performed under different conditions to determine its effect on the nanolubricants’ performance and optimal HNT concentration. The tribological performances under low and high contact pressures were analyzed with a block-on-ring tribometer following the ASTM G-077-05 standard procedure. The extreme pressure (EP) properties of the nanolubricants were determined with a T-02 four-ball tribotester according to the ITeE-PIB Polish method for testing lubricants under scuffing conditions. In addition, the lubrication performance of the newly-developed vegetable oil-based nanolubricants was evaluated in an industrial-type application through a tapping torque test. The results indicated that at a low contact pressure 1.5 wt.% HNTs/sunflower oil provided the best tribological behavior by decreasing the coefficient of friction (COF) and wear volume loss by 29 and 70%, respectively. For high contact pressures, 0.05 wt.% HNTs lowered COF and wear by 55% and 56%, respectively. The load-carrying capacity increased by 141% with 0.10 wt.% HNTs compared to the sunflower oil. A high tapping torque efficiency was obtained with HNTs that can prolong tool life in the machining process. Therefore, this study suggests that HNTs/sunflower oil could be used as green lubricants for industrial applications.

Nitrogen-Doped Carbon Dot as a Lubricant Additive in Polar and Non-polar Oils for Superior Tribological Properties via Condensation Reaction

“…This may be because the polyester film was unstable during the friction process, and the protective effect on the friction surface was weak. 27 Compared with the lubrication of 0.05 wt % CD SFO dispersion (0.05 wt %, 2 N, 200 rpm), the friction curve under 1 wt % NCD SFO dispersion lubrication was more stable, with lower friction coefficient and better lubrication effect. After doping nitrogen, which made the friction chemical reaction better, the resulting compounds further strengthened the protective film of the friction interface and reduced the friction and wear of the surface.…”

“…SFO not only has biodegradability, renewability, and environmental friendliness but also produces free fatty acids through oxidative degradation during the friction process, which is easy to form a friction polyester film with anti-wear and anti-friction effects on the friction surface. , Therefore, SFO is expected to become an environmentally friendly high-performance base oil. In addition, PAO10 is often used as a base oil to explore the effect of additives on its tribological properties. − By comparing the friction curves of SFO, PAO10, PAO4, and paraffin oil lubrication, it can be found that SFO and PAO10 show good friction reduction (Figure S1).…”

“…The friction curve under SFO lubrication showed serious instability and had a high friction coefficient. This may be because the polyester film was unstable during the friction process, and the protective effect on the friction surface was weak . Compared with the lubrication of 0.05 wt % CD SFO dispersion (0.05 wt %, 2 N, 200 rpm), the friction curve under 1 wt % NCD SFO dispersion lubrication was more stable, with lower friction coefficient and better lubrication effect.…”