REAL TIME AND IN-SITU HOLISTIC STUDY OF ENGINE TRIBOFILM FORMATION KINETICS

The current level of understanding of boundary/mixed lubricated tribological systems offers little predictive ability. Therefore, a detailed understanding of interface phenomena, especially of tribofilms' formation and removal kinetics, and their effect on friction and wear will significantly improve the process of designing new lubricants and coatings for ensuring increased fuel economy and high durability in internal combustion engines. Having the ability to characterise the tribofilm chemical composition in-contact will inevitably facilitate the studies on tribofilm formation and removal kinetics, far beyond what can be achieved currently.The proposed research project will use the X-ray absorption technique based on the latest development of the synchrotron source and the well established RAMAN spectroscopy to develop methodologies for in-situ and real time lubricated surface chemical characterisation in non-vacuum conditions. The equipment developed will be used for tribochemistry study in an engine relevant tribology system (cam/follower).While the friction of lubricated surfaces of the elastohydrodynamic interface is relatively well understood, the understanding of energy dissipation within the boundary layer regime, or at the solid-solid interface is less well understood. The project will be focused primarily in methodology and technique development for in-contact (within the rubbing contact), in-situ (within the tribotest) and in-lubro (uncleaned samples removed from the tribotest) analysis of tribochemistry processes which will be then applied to study the interface phenomena occurring in the Diamond like Carbon (DLC) coated cam/follower system when lubricated with organic friction modifier containing engine oils. The two main deliverables from this work are the development of protocols for tribology tests with in-contact and in-situ surface analysis and development of protocols for high resolution chemical in-lubro surface analysis using X-ray absorption spectroscopy. This work will enable development of a new approach for studying the tribochemistry processes occurring in sliding and rolling/sliding IC engine tribology contacts.

Who Will Benefit from this Research? 1)Lubricant/Lubricant additive and Coating Manufacturers Environmental legislation on CO2 emissions, coupled with the need to lower the operating costs and to reduce fossil fuel consumption, are increasingly pushing the Original Equipment Manufacturers (OEMs) to further improve the fuel efficiency of their vehicles. The current work will potentially provide the tools and methodologies for the development of mechanistic models that enable the optimisation of current and development of novel lubricant additives to deliver increased fuel economy. By providing lubricant manufacturers with the tools to enhance their products this project has the potential to impact directly on their competitiveness in the world market. The engine component coatings industry will benefit in similar ways to the lubricant industry. Knowledge of the mechanisms of interaction for specific coatings and the ability to make experimental measurement of actual performance will allow coatings manufacturers to optimise their products to develop low friction functionalised coatings. Another impact of low friction coatings development will be the ability of moving away from harmful lubricant additives, such as S- and P-based compounds, and development of green lubricants. 2)Original Equipment Manufacturers (OEMs) The proposed work will greatly help the OEMs in their strive to design novel fuel efficient engine tribology systems. Firstly, they will have available experimental techniques for monitoring tribochemistry in-situ and in real time - abilities not currently available to them. Development of fuel efficient tribology systems in engines will provide greater value, quantifiable as cost savings or avoidance of fines on CO2 emissions and as increasing the economic of owning a car. Another economic benefit for engine manufacturers will be the reduction in necessary engine tests for evaluation of coatings and lubricants. Mathematical models that will potentially develop following the knowledge provided by this research project will help to alleviate the need for some of these tests and the test equipment developed will help to speed up the generation of results. 3)Surface Analysis Equipment Components of the work in this project will be carried out using the Diamond Light Source national synchrotron facility in South Oxfordshire. The development of new techniques which make use of this national asset has the potential to expand the range of services Diamond Light Source Ltd (DLS) are able to provide to their users. This will effectively provide an economic benefit to both DLS and their customers and assist in providing maximum impact from the massive public investment which has gone into this national facility. How will Impact be Achieved? A workshop for industry will be held soon after completion of the project. The purpose of this will be to present the results of the research and demonstrate its potential to impact on the invitee's businesses. The companies invited will include those who have already expressed interest in the project (see letters of support), those who already work with the School of Mechanical Engineering and others from the Keyworth Institute's extensive industrial contact database. Enterprise Team staff will facilitate discussions between attendees an academics involved in the project with the aim of finding a mechanism for the two parties to work together on continuation projects/provide consultancy. The research work will be presented in the 2011 Annual Meeting of the Society of Tribologists and Lubrication Engineers (STLE) and will be published in the journal of the Society of Automotive Engineers (SAE). Results will also be presented at the Leeds-Lyon Symposium on Tribology 2011 following the end of the project. This international conference will allow still broader dissemination of the results of the project to academics and industrialists.