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

• Main Authors: Zhiqiang Tu, Enzhu Hu, Bangbang Wang, Karl D. David, Philipp Seeger, Martin Moneke, Ralph Stengler, Kunhong Hu, Xianguo Hu
• Format: Article
• Language: English
• Published: SpringerOpen 2019-03-01
• Series: Friction
• Subjects: friction; dynamics; joint clearance; numerical models; impact; durability
• Online Access: http://link.springer.com/article/10.1007/s40544-019-0272-8

Abstract 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.