Super-low friction and wear in steel contacts enabled by tribo-induced structural degradation of graphene quantum dots

Nadeem, Irfan (author), Ambrožič, Bojan (author), Dražić, Goran (author), Kovač, Janez (author), Cavaleiro, Albano (author), Kalin, Mitjan (author)

Reducing friction is a promising strategy to decrease material losses and energy consumption in industrial systems. However, in aqueous-lubricated steel contacts, the contact pressure rarely exceeds 50 MPa during super-low friction due to excessive wear. This work demonstrates that even in steel/steel contacts, by combining graphene quantum dots (GQDs) with aqueous glycerol, it is possible to maintain super-low friction (µ ≈ 0.012) under a contact pressure as high as 316.5 MPa. Moreover, the use of GQDs improved the wear performance by 98 % compared to pure aqueous glycerol due to the formation of a tribochemical film, resulting from the electrostatic adsorption of GQDs on the positively charged sites on the worn surface. In particular, the exfoliation of graphene sheets within GQDs, the shearing of graphene layers inside the GQDs, and the OH–OH repulsion between the asperities shortens the running-in period and consequently reduces the friction and wear. At the same time, the formation of a chemically adsorbed tribofilm containing friction-induced structurally degraded GQDs protects the surface from wear and facilitates the maintenance of super-low friction at high contact pressures by improving the load-carrying capacity. This study suggests that green nano-lubricants based on GQDs have immense potential in sustainable engineering.

• Language: English
• Keywords: materials, graphene, quantum dots, tribology, friction, wear
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2024
• Number of pages: 14 str.
• Numbering: Vol. 244, art. 113111
• PID: 20.500.12556/RUL-159197
• UDC: 539.92
• ISSN on article: 0264-1275
• DOI: 10.1016/j.matdes.2024.113111
• COBISS.SI-ID: 200420867
• Publication date in RUL: 03.07.2024

Record is a part of a journal

• Title: Materials & design
• Shortened title: Mater. des.
• Publisher: Scientific and Technical Press
• ISSN: 0264-1275
• COBISS.SI-ID: 10626075

Licences

• License: CC BY-NC 4.0, Creative Commons Attribution-NonCommercial 4.0 International
• Link: http://creativecommons.org/licenses/by-nc/4.0/
• Description: A creative commons license that bans commercial use, but the users don’t have to license their derivative works on the same terms.

Secondary language

• Language: Slovenian
• Keywords: materiali, grafen, kvantne pike, tribologija, trenje, obraba