Effect of surface modification of Al ₂ O ₃ on its tribological properties

Purpose This paper aims to investigate the preparation of Nano-Al 2 O 3 lubricant, as well as the effect of surface modification of Al 2 O 3 on friction and wear properties. Design/methodology/approach The chemical parameters such as the energy levels of the Highest Occupied Molecular Orbital, the Lowest Unoccupied Molecular Orbital and the Fukui indices of seven modifiers, including myristic acid myristyl ester, glycerol trioleate, acetyl monoethanolamine, docosanamide, Tween-60, dodecyl dihydroxyethyl amine oxide and sodium dodecyl sulfate (SDS), are calculated by using the Materials Studio software. Meanwhile, the adsorption energies of these seven modifiers on Al 2 O 3 nanoparticles are also calculated. Based on the simulation results, SDS and Tween-60 were identified as the most effective surface modifiers. Modified lubricants were prepared with Al 2 O 3 nanoparticles at varying concentrations (0.1–0.4 Wt.%). Their tribological properties, including the maximum nonseizure load ( P B ) and the coefficient of friction (COF), were evaluated using a four-ball wear tester. The worn surfaces were analyzed by scanning electron microscopy and three-dimensional profilometry. Findings The results indicate that SDS improves both the extreme pressure and anti-wear performance of the lubricant. The lubricant achieves optimal performance when combined with 1.0 Wt.% SDS and 0.2 Wt.% nano-Al 2 O 3 . At this combination, the value of PB reaches 209 N, and the value of COF is approximately 0.072. Compared to the unmodified Al 2 O 3 lubricant with a COF of 0.086, this represents a 23% reduction in COF. Originality/value Modified Al 2 O 3 lubricants demonstrate superior lubrication performance and effectively reduce the COF, providing valuable insights for the practical application of nanolubricants. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-09-2024-0353/