Friction and wear improvement by using Curcumin as a natural additive in green lubricants

Lubrication is an essential mechanism to make machines and engines more efficient by lowering friction and wear. Despite this, to mitigate environmental damage, lubricants must come from renewable sources and be biodegradables. Therefore, this study analyzed the use of Curcumin as a natural additive in two green oils to improve their tribological and oxidative performance. The density and viscosity of lubricants with and without curcumin additive, as well as the lubrication regime, were determined. The operational performance was analyzed by tribological tests under a ball-on-disk configuration at 100 degrees C based on the ASTM G99. The oxidative behavior of lubricants was examined by studying the IR bands for primary and secondary oxidative products, as well as by DSC-TGA techniques for evaluating the Oxidation Onset Temperature and the thermogravimetric behavior. At the studied conditions, the incorporation of Curcumin into the oils increased the viscosity of the lubricants up to 46%, the friction coefficient decreased up to 70%, and wear was diminished up to 96%, despite working in boundary lubrication. Moreover, the addition of curcumin noticeably enhanced the oxidation behavior of lubricants. The results of this research suggest that Curcumin is an excellent option to improve the physical properties, operational performance, and oxidative stability of green oils to create effective and environmentally friendly lubricants.