Shear-driven reactions of organosulfur compounds on ferrous surfaces: A molecular dynamics study

• Published in: Tribology international 2022-12, Vol.176, p.107922, Article 107922
• Main Authors: Mohammadtabar, Karen, Eder, Stefan J., Dörr, Nicole, Martini, Ashlie
• Format: Article
• Language: English
• Subjects: Additives; Mechanochemical; Molecular simulation
• ISSN: 0301-679X; 1879-2464
• DOI: 10.1016/j.triboint.2022.107922

Reactive molecular dynamics simulations were used to investigate reactions between di-tert-butyl disulfide and ferrous surfaces. Tribochemical reactions were characterized with and without a model base oil, n-dodecane, and on either Fe(100) or H-passivated Fe2O3 surfaces. Reaction yield increased with both temperature and pressure for all model systems. The presence of the base oil did not significantly affect the reaction yield or pathway, but the base oil impeded transmission of shear stress to the reactants. Replacing the ideal Fe(100) with H-passivated Fe2O3 surfaces enabled reaction pathways involving oxygen from the surface and decreased the reaction yield. The rate-limiting step of the reactions was analyzed in the context of the Bell model as a step towards better understanding tribochemical reactions. [Display omitted] •Reactions of di-tert-butyl disulfide on ferrous surfaces were modeled•Reactions on iron oxide had lower yield and different pathways than on Fe(100)•The presence of O and H impeded iron sulfide formation•Base oil lowered pressure-dependence of reaction yield due to molecular alignment