Optimizing lubrication in step slider bearings : the role of oiliness additives on film formation and friction reduction

Jing, Zhaogang (author), Dong, Haoyu (author), Jin, Wei (author), Guo, Feng (author), Kalin, Mitjan (author), Li, Ziying (author), Wang, Dong (author), Ju, Chao (author)

This study examines how the molecular structures of oiliness additives affect the lubrication performance of a step slider bearing. Here an optical step-slider-on-disc tribometer was used to measure interferometric film thickness together with friction force under the present test conditions. Seven representative molecules (undecanedioic acid, undecanoic acid, palmitic acid, stearic acid, oleic acid, oleylamine and oleyl alcohol) were each blended into PAO8 at 0.15 wt% to separately probe headgroup polarity, alkyl-chain length, saturation and the number of polar heads. Compared with neat PAO8, every formulation produced a thicker film (up to 106% increase) and a lower coefficient of friction (up to 65.9% reduction), with stearic acid delivering the best overall improvement. To interpret the trends, wettability of the step-slider surface after lubricant treatment was assessed by deionized-water contact-angle measurements. The observed inlet–outlet wetting asymmetry is consistent with a possible asymmetry in interfacial slip, which may contribute to the experimentally observed combination of film-thickness increase and friction reduction.

• Language: English
• Keywords: oiliness additives, surface adsorption films, step slider bearing, optical interferometry, film thickness, interfacial slip
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Author Accepted Manuscript
• Year: 2026
• Number of pages: Str. 1-10
• Numbering: Vol. 222, art. 112134
• PID: 20.500.12556/RUL-183418
• UDC: 539.92:539.37:669.14
• ISSN on article: 0301-679X
• DOI: 10.1016/j.triboint.2026.112134
• COBISS.SI-ID: 278637315
• Publication date in RUL: 12.06.2026

Record is a part of a journal

• Title: Tribology international
• Shortened title: Tribol. int.
• Publisher: Elsevier
• ISSN: 0301-679X
• COBISS.SI-ID: 26558976

Licences

• License: CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
• Link: http://creativecommons.org/licenses/by-nc-nd/4.0/
• Description: The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.

Secondary language

• Language: Slovenian
• Keywords: eksperiment z aspernostjo na terenu, večaspernostni stiki, realna kontaktna površina, utrjevanje, deformacija, jeklo, hrapavost