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Effect of dispersant concentration with friction modifiers and anti-wear additives on the tribofilm composition and boundary friction

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journal contribution
posted on 02.02.2021, 16:39 by Jamal Umer, Nick MorrisNick Morris, Ramin RahmaniRamin Rahmani, Homer Rahnejat, Sebastian Howell-Smith, Sashi Balakrishnan
To extend drain intervals and improve efficiency, new engine oils with increased dispersant concentration and reduced viscosity are required. Low viscosity engine oils can increase the prevalence of boundary friction at low temperature and increase its severity at higher temperatures. As a result, combinations of organic and inorganic friction modifiers (FM) will be used to reduce boundary friction across a range of temperatures, also preventing damage to vehicle catalysts. This paper presents an experimental case study of such new generation of fully-formulated engine lubricants with varying concentrations of polyisobutylene succinimide dispersant, organic and inorganic FM. Representative conditions pertaining to those encountered at the top dead centre reversal of the piston compression ring-cylinder liner contact are created, and the generated friction measured through use of a sliding-strip tribometry. Subsequently, X-Ray Photoelectron Spectroscopy (XPS) is used to determine the composition of the formed surface tribofilms in order to explain the observed frictional characteristics. The key interactions and frictional behaviour of the dispersant and friction modifiers are highlighted across a range of operating temperatures.

Funding

EPSRC Centre for Doctoral Training in Embedded Intelligence

Engineering and Physical Sciences Research Council

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University of Engineering and Technology Lahore

History

School

  • Mechanical, Electrical and Manufacturing Engineering

Published in

Journal of Tribology

Volume

143

Issue

11

Publisher

American Society of Mechanical Engineers

Version

AM (Accepted Manuscript)

Rights holder

© ASME

Publisher statement

This paper was accepted for publication in the journal Journal of Tribology and the definitive published version is available at https://doi.org/10.1115/1.4050017.

Acceptance date

25/01/2021

Publication date

2021-02-23

Copyright date

2021

ISSN

0742-4787

eISSN

1528-8897

Language

en

Depositor

Dr Nick Morris. Deposit date: 18 January 2021

Article number

111901