LECTURE
How Surface Topography and Chemistry Control Lubrication
Biography
Juliette Cayer-Barrioz graduated in Physics from the University of Grenoble in 1998 and in Mechanical Engineering from the Ecole Centrale de Lyon (ECL) in 2000 before obtaining her PhD in Materials Science from ECL in 2003 and her Habilitation in Mechanics in 2011. Since 2005, she has been associated with the French National Centre for Scientific Research (CNRS). Her research activities at the Laboratoire de Tribologie et Dynamique des Systèmes (LTDS) in Ecole Centrale de Lyon focus on surface phenomena and dynamics of confined lubricated interfaces. Her multidisciplinary approach—based on unique experimental devices developed at the LTDS—combines physics, interfacial chemistry and mechanics, rheology and friction.
After an eight-year contribution to the Laboratoire d’Excellence Manutech-Sise, she served for four years as a member of the French National Committee of the CNRS in mechanics. She is an editor of Tribology Letters. Her teaching activities at ECL, and beyond, address the physics and chemistry of interfaces and the rheology of complex media. She was awarded the 2025 Peter Jost Award in Tribology.
Abstract
Juliette Cayer-Barrioz
Laboratoire de Tribologie et Dynamique des Systèmes, CNRS UMR5513, Ecole centrale de Lyon, France
The idea of using a liquid to separate two solid surfaces in contact under pressure is not new. This thin lubricating film can
support a load, reduce energy losses, protect the surfaces from wear and corrosion, remove wear debris and dissipate heat.
Thus, lubrication mechanisms can be examined in terms of film-forming capacity and friction dissipation. The lubricated
contact is a complex system whose behaviour and evolution are influenced by the interfacial geometry at the macro- and
micro-scales, the tribological conditions and the rheology of the lubricant. The high contact stresses can cause it to act as a
‘mechano-chemical reactor’ to trigger reactions of the lubricant and its additives to form tribofilms and/or influence the
adsorption of boundary layers. These complex interfaces are investigated here by integrating experimental, numerical and
theoretical approaches. It covers all lubrication regimes, from the thin full-film regime, in which deformed surfaces are fully separated by a pressurised fluid film, to the boundary lubrication regime, in which protruding asperities come into contact.
The experimental approach spans a wide range of spatial and time scales; film thicknesses range from nanometres to
hundreds of nanometres and timescales from a few hundredths of a milliseconds to essentially quasistatic sliding. This
approach was used to provide a fundamental understanding of a wide range of phenomena from film formation under
oscillating contacts, friction reduction by the control of adsorbed films and molecular organization on the surface, the
influence of surface roughness and texturing on lubrication regime transitions, aqueous lubrication… The capabilities of this integrated theoretical and experimental approach are illustrated to demonstrate the importance of surface topography and the physical chemistry on friction, as well as showing how complex fluids can lubricate the surface to provide a detailed understanding the mechanisms occurring within lubricated contacts. This presentation will focus of how these fundamental insights can have had a significant impact on society and the environment.
