Tribological behaviors of Ni-modified citric acid carbon quantum dot particles as a green additive in polyethylene glycol

• Published in: Friction 2020-02, Vol.8 (1), p.182-197
• Main Authors: Tu, Zhiqiang, Hu, Enzhu, Wang, Bangbang, David, Karl D., Seeger, Philipp, Moneke, Martin, Stengler, Ralph, Hu, Kunhong, Hu, Xianguo
• Format: Article
• Language: English
• Subjects: Carbon; Citric acid; Coefficient of friction; Corrosion and Coatings; durability; dynamics; Engineering; Friction; Green chemistry; impact; joint clearance; Lubrication; Mechanical Engineering; Nanoparticles; Nanotechnology; Nickel; numerical models; Physical Chemistry; Polyethylene glycol; Quantum dots; Reciprocation; Research Article; Surfaces and Interfaces; Thin Films; Tribology; Wear mechanisms; Wear rate
• ISSN: 2223-7690; 2223-7704
• DOI: 10.1007/s40544-019-0272-8

A novel green lubricating oil additive (carbon quantum dot (CQD) particle-doped nickel (Ni-CQD)) was synthesized from citric acid and nickel acetate. The effects of CQD and Ni-CQD nanoparticles on the tribological behaviors of polyethylene glycol (PEG200) were investigated under different loads and reciprocation speeds. The results indicate that CQD and Ni-CQD particles can both enhance the lubrication properties of PEG200. However, the Ni-CQD nanoparticles enhanced the lubrication properties more than the plain CQD particles did. The average friction coefficient and wear rate of PEG200 containing 2 wt% Ni-CQDs were reduced by 35.5% and 36.4%, respectively, compared to PEG200 containing pure CQDs under a load of 8 N and reciprocation speed of 25 mm/s over 60 min. The friction and wear mechanisms are attributed to the fact that friction induces the Ni-CQDs to participate in the formation of a tribofilm, resulting in a low friction coefficient and wear rate.