Mechanochemistry in Lubrication

Completed

Energy Efficiency(Transport)
Not Energy Related
Energy Efficiency(Industry)

Basic and strategic applied research

PHYSICAL SCIENCES AND MATHEMATICS (Chemistry)
ENGINEERING AND TECHNOLOGY (Mechanical, Aeronautical and Manufacturing Engineering)

Not Cross-cutting

Professor HA Spikes
Department of Mechanical Engineering
Imperial College London

Standard

EPSRC

01 August 2017

31 July 2021

48 months

£578,903

Mechanical engineering

London

NC : Engineering

Professor HA Spikes, Department of Mechanical Engineering, Imperial College London

Dr D Dini, Department of Mechanical Engineering, Imperial College London
Dr J Wong, Department of Mechanical Engineering, Imperial College London

Project Contact, Afton Chemicals, USA
Project Contact, Tohoku University (Japan)
Project Contact, SKF Engineering & Research Services B.V., The Netherlands
Project Contact, Shell Global Solutions UK
Project Contact, Uganda Red Cross Society
Project Contact, PCS Instruments

Improvements in lubricant technology are needed to reduce friction in machines and thus save energy and control global warming. Lubricants consist of a mineral or synthetic oil in which are dissolved up to ten or so chemical additives. The most important of these additives are friction and wear-reducing agents. These react with rubbing metal surfaces to form thin protective films that, as their names suggest, give low friction and wear. These films form only when surfaces rub together so they are often called "tribofilms".Until recently we had very little idea of what caused tribofilms to form - was it the high temperature or pressure in rubbing contacts, or the metals becoming activated in some way by rubbing? This ignorance made it almost impossible to design additives except by trial and error or to build models their behaviour. However earlier this year it was shown conclusively that the most widely-used antiwear additive reacts in rubbing contacts because of the high shear forces present. These forces stretch the bonds in the molecules until they break, which leads to chemical reaction to form a tribofilm. This concept, of applied forces driving chemical reactions, is quite well known in modern chemistry and is called mechanochemistry. But this is the first time it has been shown indubitably to control tribofilm formation in the field of lubrication. It is very important insight since it points the way to us being able to predict how particular additive molecular structures will behave in rubbing contacts and thus design better additives to give lower friction and less wear.The current project will explore the full significance of mechanochemistry to lubricant design and use. It will test which types of lubricant additive reaction are driven by shear forces and develop quantitative relations between reaction rate, applied shear force and temperature so as to enable modelling to proceed. It will look at a range of model antiwear additives with different but related structures to identify which bonds break to precipitate tribofilm formation - thereby enabling molecular structure to be optimised. It will also follow the reaction sequence that results from initial bond breaking to tribofilm formation by looking into rubbing contacts (with one transparent surface transparent) using chemical spectroscopy. All of this will be done in specially-designed test equipment that is able to reach the very high contact shear forces normally present in solid-solid rubbing contact conditions and that drive the chemical reactions involved.The overall goal is to understand, for the first time and through the use of advanced experimental and modelling techniques, how lubricant additives react in rubbing contacts to form low friction and low wear films, and so to enable new and more energy-saving lubricants to be designed in future.

25/01/19