Ascorbyl Palmitate-Vitamin C Effective Friction Modifier and Wear Inhibitor for Steel in a PAO Base Oil

Ascorbyl palmitate (AP), known as a nutrition pill, and an antioxidant agent in food, has demonstrated excellent lubricity as an additive in PAO4. Adding one wt% AP in PAO4 drastically decreases friction Coefficient (CoF) up to 66% and protects the steel surface from wear. Meanwhile, it shows a more vital friction reduction ability than conventional Mo-based additives and fatty acids, especially palmitic acid. Ascorbic acid core on AP optimises palmitic acid lubricity by forming robust chemical C-O-Fe bond on steel, increasing surface coverage rate. Masked by AP self-assembled layers, steel surfaces can also handle extreme pressure (up to 2.34 GPa) and temperature (150 °C) with unmeasurable wear. This work broadens human-friendly AP vitamin C application for industrial use and introduces a new pathway for optimizing fatty acids lubricity.