Superior macro-scale tribological performance of steel contacts based on graphene quantum dots in aqueous glycerol

Nadeem, Irfan (author), Malok, Matjaž (author), Kovač, Janez (author), Yaqub, Talha Bin (author), Cavaleiro, Albano (author), Kalin, Mitjan (author)

Reducing friction is one of the best ways to lower energy consumption and make processes more environmentally friendly. Because of the growing interest in green lubricants, we investigated the synergetic effects of graphene quantum dots (GQDs) combined with aqueous glycerol to improve the lubrication performance of self-mated steel contacts in reciprocating sliding motion. As a comparison, the lubrication performance of some other two-dimensional (2D) graphitic materials (graphite, graphene oxide, and graphene nanoplatelets) was also studied. The results demonstrate that the GQDs-based nano-lubricant reduces the running-in period and provides super-low friction at a high contact pressure in the boundary-lubrication regime, with 72% and 53% improvements in anti-friction and anti-wear performance compared with aqueous glycerol. On the other hand, the 2D graphitic materials provide super-low friction in the mixed-lubrication regime due to the dominant polishing effect of the hydroxyl groups. The surface Raman mapping indicates that the 2D graphitic materials were severely damaged by the continuous reciprocating motion owing to their inferior crack resistance. In contrast, the superior deformation resistance of the GQDs helps to develop a tough tribofilm. This lubrication mechanism suggests that internal shearing of graphene layers inside the GQDs significantly reduces the wear and friction during the running-in period, while the in-situ formation of strongly adhered tough tribofilm with more surface coverage contributed to the realization of super-low friction under a high contact pressure. This study demonstrated that GQDs-based green nano-lubricants could provide super-low friction at a high contact pressure in the boundary-lubrication regime, which was so far characteristic mainly for conventional environment-polluting lubricants.

• Language: English
• Keywords: graphene, graphene quantum dots, graphite, aqueous glycerol, super-low friction, green tribology
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2023
• Number of pages: 15 str.
• Numbering: Vol. 181, art. 108328
• PID: 20.500.12556/RUL-148685
• UDC: 539.92
• ISSN on article: 1879-2464
• DOI: 10.1016/j.triboint.2023.108328
• COBISS.SI-ID: 144799747
• Publication date in RUL: 29.08.2023

Record is a part of a journal

• Title: Tribology international
• Shortened title: Tribol. int.
• Publisher: Elsevier
• ISSN: 1879-2464
• COBISS.SI-ID: 62108419

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: grafen, grafenske kvantne pike, grafit, vodni glicerol, super nizko trenje, zelena tribologija