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Mechanochemistry for Decomposition of Antiwear Additives on Ferrous Surfaces: A REAXXFF Study of Phosphate Esters

Carlos Ayestarán Latorre

Department of Mechanical Engineering

Monday 12th April 2021
Time: 12pm
Venue: Online
Contact: Ms Hafiza Bibi

Abstract: Mechanochemistry plays a pivotal role in antiwear additives which are critical to maintain the reliable operation of internal combustion engines and many other machine components. When exposed to shear, these additives form protective tribofilms on the sliding surfaces. Reactive molecular dynamics simulations provide a crucial opportunity to understand the chemistry of these processes at the atomic scale and the role of surfaces and molecular structures. In this study, we first investigate the thermal decomposition of phosphate esters with different molecular substituents on ferrous and ferrous oxide surfaces to compare the rate-limiting mechanisms suggested by previous experiments in the literature. Secondly, we perform sliding-wall simulations to study the decomposition under shearing conditions. We find that the decomposition rates increase exponentially with temperature and stress, which is indicative of a stress-augmented thermally activated reaction.

 

Other authors: James P. Ewen, Arash Khajeh, Ashlie Martini, Joshua D. Moore, Joseph E. Remias, Daniele Dini.

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