Robust and durable superlubricity enabled by carboxylated graphene quantum dots in lubricated steel contacts

Nadeem, Irfan (avtor), Finšgar, Matjaž (avtor), Dražić, Goran (avtor), Malok, Matjaž (avtor), Morina, Ardian (avtor), Kalin, Mitjan (avtor)

Achieving macroscale superlubricity on engineering steel by utilizing aqueous green lubricants has gained growing interest, given its substantial potential to reduce energy consumption and carbon footprint. However, maintaining superlubricity under diverse sliding conditions over a prolonged duration is a major obstacle for real-scale applications. Herein, we report that a robust and durable tribofilm enabled by a unique lubrication mechanism based on carboxylated graphene quantum dots (CGQDs) in aqueous glycerol triggers macroscale superlubricity in self-mated steel contacts. A dedicated intermittent test was designed to show the superlubricity's robustness and the ability of the tribofilm to adapt to a variety of relevant sliding conditions. Moreover, the boundary film provides an average coefficient of friction of around 0.007 and up to 69 % wear reduction (compared to the base lubricant), resulting in the maintenance of superlubricity at a real final contact pressure of 123 MPa, which increases the upper limit of the contact pressure compared to current aqueous-lubricated steel contacts. The new superlubricity mechanism was enabled by the chemical adsorption of the CGQDs onto the worn metal surface, coupled with the tribo-induced structural degradation and transformation of the CGQDs into layered graphitic structures that generate an adaptable low-shear interface. This work provides new insights into the role of chemical adsorption and structural transformation of CGQDs in achieving superlubricity and is an important step forward for implementing energy-efficient and green lubrication technologies for industrial applications.

• Jezik: Angleški jezik
• Ključne besede: graphene quantum dots, superlubricity, boundary lubrication, aqueous glycerol, green tribology, steel
• Vrsta gradiva: Članek v reviji
• Tipologija: 1.01 - Izvirni znanstveni članek
• Organizacija: FS - Fakulteta za strojništvo
• Status publikacije: Objavljeno
• Različica publikacije: Objavljena publikacija
• Leto izida: 2024
• Št. strani: 16 str.
• Številčenje: Vol. 226, art. 119226
• PID: 20.500.12556/RUL-156374
• UDK: 539.92:621.8
• ISSN pri članku: 1873-3891
• DOI: 10.1016/j.carbon.2024.119226
• COBISS.SI-ID: 196343811
• Datum objave v RUL: 23.05.2024

Gradivo je del revije

• Naslov: Carbon
• Založnik: Elsevier
• ISSN: 1873-3891
• COBISS.SI-ID: 22990853

Licence

• Licenca: CC BY-NC-ND 4.0, Creative Commons Priznanje avtorstva-Nekomercialno-Brez predelav 4.0 Mednarodna
• Povezava: http://creativecommons.org/licenses/by-nc-nd/4.0/deed.sl
• Opis: Najbolj omejujoča licenca Creative Commons. Uporabniki lahko prenesejo in delijo delo v nekomercialne namene in ga ne smejo uporabiti za nobene druge namene.

Sekundarni jezik

• Jezik: Slovenski jezik
• Ključne besede: grafenske kvantne pike, super mazljivost, mejno mazanje, vodni glicerol, zelena tribologija, jeklo