Application of graphene-based additives in environmentally friendly aqueous lubricants to enhance friction and wear performance

The acceleration of market penetration of fully electrified vehicles (EVs) is expected to be significant over the next 15-20 years, reaching 30% in the USA alone.

A 2022 report by the Society of Tribologists and Lubrication Engineers (STLE) details how an estimated $300bn has been invested into electrified powertrain research and development via global automotive original equipment manufacturers (OEMs) already. Moreover, there is significant industrial interest in the provision of bespoke lubricants for electric drive units (EDUs). The EDU lubricants in some circumstances (e.g. BMW e-drive) provide more than one function: drivetrain lubrication and electric motor cooling. The optimised lubricant must provide cooling, minimise wear, promote machine element durability, vast material compatibility, whilst enabling high efficiency EDUs, a key pillar in achieving sustainable mobility globally.

Aqueous lubricants, with the appropriate additive package, could provide substantially improved cooling and reduced frictional power losses in EDUs and mitigate environmental concerns associated with conventional fossil-derived lubricants. The speed-load duty cycles of electric powertrains differ from their combustion propelled counterparts, and therefore justify the development of a bespoke environmentally friendly lubricating fluid. The fluid must provide protection against high loads at low speed, whilst not suffering large churning losses at high speeds. Furthermore, the lubricant will be subject to electromagnetic (EM) fields, which is a topic area with little to no understanding regarding the implications for the lubricant and its associated additive package.

 Graphene-based additives are proposed by tribologists as effective substances to enhance the friction and wear performance of aqueous lubricants, although their application in electromagnetic environment of EDUs has not been investigated hitherto. The hypothesis in this research is that application of an optimised graphene-based additive in aqueous lubricant will increase the wear protection and reduce the friction for EDUs. This will enable their implementation in electric powertrains leading to other benefits such as better cooling, simpler system design by combining lubrication and cooling and introducing a green lubricant. The ambition of the created research stream will be to see water-based lubricants in EDUs in the near future. The proposed research will be novel, challenging and adventurous.

This research will be conducted using experimental and numerical methods to form a comprehensive scientific platform for discovering the tribological performance of proposed lubricants. Additives will be fabricated, characterised and prepared/mixed in the based aqueous lubricant. Their wear and friction performances will then be investigated using Conductive Atomic Force Microscope (C-AFM) at asperity level, a tribometer and contact level and a bearing test rig at component level. This set of equipment are all available at Loughborough University. The friction and wear measurement is in-situ, but the formation of potential tribo-film (more permanent build-up of additives on the surface) will be characterised ex-situ using combination of FIB and TEM, FTIR and XPS. The experimental campaign will provide a solid understanding of the friction and wear behaviour under electromagnetically charged aqueous lubricants with added graphene-based additives, but numerical simulation will be needed to expand the range of working conditions (load, speed, electromagnetic range, temperature) and the application (to other than bearings) in preparation for higher impacts. This will be performed using in-house available simulation models, enriched by rheological, surface and material properties of proposed lubricant and additives.

The outcome of this research will spark a high-impact research stream at Loughborough University, opening new horizon for follow-up research proposals, high quality and high-impact publications and international visibility and influence. The mid to long term outcome of this research may also lead to significant commercialisation opportunities by licensing generated technologies related to the proposed lubricants.

Supervisors

Primary supervisor: Dr Mahdi Mohammad-Pour

Secondary supervisor: Dr Manuela Pacella

Entry requirements for United Kingdom

Successful applicants should have, or expect to achieve, an undergraduate honours degree with a minimum classification of a 2:1, or equivalent in a relevant subject for the PhD topic. A relevant master’s degree and/or experience would also be advantageous.

English language requirements

Applicants must meet the minimum English language requirements. Further details are available on the International website.

How to apply

All applications should be made online. Under programme name, select ‘Mechanical, Electrical and Manufacturing Engineering’. Please quote reference number: P1SAM23-05 in your application. 

Competition for funded entry is high so please ensure that you submit a CV and the minimum supporting documents by the advert closing date. Failure to do so will mean that your application will not be taken forward for consideration. See studentship assessment criteria.

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