Development of New Precursors for Lubricious Coatings

Antiwear and reduced friction agents are a class of engine oil additives used to both reduce self-inflicted damage from metal-metal contact inside internal combustion engines, as well as acting as friction modifiers, which serves to improve engine efficiency. Zinc dialkyl dithiophosphates are one of the leading materials used as such agents. However, despite their effectiveness, they are known to contaminate catalytic converters - a problematic issue which has led to significant research into finding replacements. Although the electrification of the transport industry has already started, tribology and the design and formulation of antiwear and antifriction additives play an important role in the optimisation of efficiency of every mechanical device. Extensive use of zinc dialkyldithiophosphates and other materials such as molybdenum disulphide (MoS2) as antiwear and lubricious materials are present across many applications that involve devices with moving mechanical components.
This PhD proposes to expand upon this area of research starting from a new perspective on the topic of wear and tribochemistry by investigating new inorganic materials as protective coatings. The aim of this project is to synthesise a range of precursor complexes and to assess their potential application in the formation of either friction-reduction thin films.
Objectives: modern ICEs contain a plethora of working parts coated with protective anti-wear or friction reducing coatings ranging from SiO2, TiO2, CrN and diamond. Our initial focus in this project will be directed toward the targeting and formulation of specific materials identified by their know application such as MoS2 or WS2, which have been known for some time to display lubricious behaviour at high temperatures. These materials and their derivatives exhibit intrinsic defects which in turn results in the formation of Shear planes. It is these Shear planes which under stress, can facilitate sliding and contribute to the lubricious nature of these materials. Addition of soft cations, such as silver and potassium, as dopants has also been shown to affect the formation of materials with desirable friction coefficients. Following a series of pre-established design criteria, i.e. precursors should be hydrolytically stable; soluble in higher hydrocarbon fractions (C8-C20), low toxicity; display a heat induced degradation in oil; as well as the final oxide material displaying a high thermal stability. Intrinsic to the development of any prospective precursor, studies will involve the following: assessment of the precursor and their properties with respect to thermal screening, composition of thin films formed and their characterisation; stability and solubility studies; as well as mechanical trials for example using pin-on-disc reciprocating rigs and ultra-shear viscometers, allowing for relevant information on the thin film formed to be fed back into precursor design. Targets within the first 3 months include development of ligand frameworks suitable for supporting homometallic systems containing which the desired elements for the final lubricious thin film. Initial Focus is directed towards the development of new precursors for molybdenum and tungsten sulphide systems. Supervisor Contributions: The primary supervisor (Dr Andrew Johnson) is to direct the project given his expertise in deposition of thin film materials and in precursor design. Primary supervisor contribution weighting: 80%. The secondary supervisor (Prof Matt Jones) is to advise the project given his expertise in ligand development and inorganic coordination chemistry Secondary supervisor contribution weighting: 20%.
The vision of the EPSRC is to advance the knowledge and technology of scientists to tackle several key areas one of which is climate change. The development of novel lubricious materials aids in the reduction of carbon, not only lowering the effefcts of climate change but conserving the current environment.

Impact Summary

This proposal has been developed from the ground up to guarantee the highest level of impact. The two principal routes towards impact are via the graduates that we train and by the embedding of the research that is undertaken into commercial activity. The impact will have a significant commercial value through addressing skills requirements and providing technical solutions for the automotive industry - a key sector for the UK economy.

The graduates that emerge from our CDT (at least 84 people) will be transformative in two distinct ways. The first is a technical route and the second is cultural.

In a technical role, their deep subject matter expertise across all of the key topics needed as the industry transitions to a more sustainable future. This expertise is made much more accessible and applicable by their broad understanding of the engineering and commercial context in which they work. They will have all of the right competencies to ensure that they can achieve a very significant contribution to technologies and processes within the sector from the start of their careers, an impact that will grow over time. Importantly, this CDT is producing graduates in a highly skilled sector of the economy, leading to jobs that are £50,000 more productive per employee than average (i.e. more GVA). These graduates are in demand, as there are a lack of highly skilled engineers to undertake specialist automotive propulsion research and fill the estimated 5,000 job vacancies in the UK due to these skills shortages. Ultimately, the CDT will create a highly specialised and productive talent pipeline for the UK economy.

The route to impact through cultural change is perhaps of even more significance in the long term. Our cohort will be highly diverse, an outcome driven by our wide catchment in terms of academic background, giving them a 'diversity edge'. The cultural change that is enabled by this powerful cohort will have a profound impact, facilitating a move away from 'business as usual'.

The research outputs of the CDT will have impact in two important fields - the products produced and processes used within the indsutry. The academic team leading and operating this CDT have a long track record of generating impact through the application of their research outputs to industrially relevant problems. This understanding is embodied in the design of our CDT and has already begun in the definition of the training programmes and research themes that will meet the future needs of our industry and international partners. Exchange of people is the surest way to achieve lasting and deep exchange of expertise and ideas. The students will undertake placements at the collaborating companies and will lead to employment of the graduates in partner companies.

The CDT is an integral part of the IAAPS initiative. The IAAPS Business Case highlights the need to develop and train suitably skilled and qualified engineers in order to achieve, over the first five years of IAAPS' operations, an additional £70 million research and innovation expenditure, creating an additional turnover of £800 million for the automotive sector, £221 million in GVA and 1,900 new highly productive jobs.

The CDT is designed to deliver transformational impact for our industrial partners and the automotive sector in general. The impact is wider than this, since the products and services that our partners produce have a fundamental part to play in the way we organise our lives in a modern society. The impact on the developing world is even more profound. The rush to mobility across the developing world, the increasing spending power of a growing global middle class, the move to more urban living and the increasingly urgent threat of climate change combine to make the impact of the work we do directly relevant to more people than ever before. This CDT can help change the world by effecting the change that needs to happen in our industry.