Dynamic chemisorption and tribochemistry of α-lipoic-acid-ester on ferrous surfaces

• Published in: Tribology international 2024-04, Vol.192, p.109291, Article 109291
• Main Authors: Ruan, Xiaopeng, Wang, Xiaomei, Zhou, Rui, Zhao, Yang, Bao, Luyao, Zhou, Feng, Lu, Zhibin
• Format: Article
• Language: English
• Subjects: Tribochemistry • Tribofilm • Reactive molecular dynamics simulation • α-Lipoic acid ester
• ISSN: 0301-679X; 1879-2464
• DOI: 10.1016/j.triboint.2024.109291

Tribofilm formation and growth play a vital role in friction reduction and antiwear enhancement. However, our understanding at the atomic level, particularly from a tribochemical viewpoint, is limited. Here, we elucidate α-lipoic acid ester tribofilm formation on ferrous interfaces using reactive molecular dynamics simulations. Our findings uncover a sequence where chemisorbed films initially develop through Fe-S bonding, followed by decomposition (C-O, C-S bonds) and polymerization reactions (S-S, S-O bonds). Thermal and mechanical forces collaboratively facilitate this process. The kinetic analysis demonstrates elevated activation volume exhibited a negative correlation with the reaction frequency difference. Normal stress boosts reactivity by encouraging the polymerization and reducing activation energy. This work offers a comprehensive understanding of α-lipoic acid ester tribofilm formation on ferrous interfaces. •Reactions of α-lipoic acid ester on the ferrous surface were modeled.•Four basis reaction paths were found and the reaction network was built.•Activation volume exhibited a negative correlation with the total reaction frequency difference.•The normal stress promote the polymerization reaction and lowering the activation energy.