Materials
Contact Dynamics
About
The Contact Dynamics group studies friction, adhesion and wear in contacts that must operate with extreme precision. Understanding where friction comes from, why it changes over time, and how it can be controlled is both a fundamental scientific challenge and a route toward more reliable chip manufacturing.
Research focus
The Contact Dynamics group aims to understand and control friction, adhesion and wear from the atomic to the macroscopic scale. Our central question is how small-scale interfacial processes determine the frictional response of practical contacts in nanolithography. These phenomena are central to nanolithography in which wafers are repeatedly positioned and accelerated with nanometer-scale accuracy, while small variations in friction can lead to positional errors.
Our research focuses on stiff, rough material interfaces such as silicon, oxide and diamond-like surfaces. At these interfaces, contact occurs only at many microscopic asperities, where stresses, chemical reactions, wear particles, humidity and electric fields can all influence the macroscopic friction force. We investigate how these local processes combine to determine sliding behavior, adhesion and material removal.
To do this, we combine custom-built tribology experiments with optical visualization, atomic-force microscopy, surface analysis and controlled-environment measurements. A central aim is to make friction and wear measurable while they happen: to connect changes in force to changes in real contact area, surface topography, interfacial chemistry and wear-particle dynamics.
Real surfaces touch only at a distribution of microscopic contact points. We study how roughness, contact size, loading history and sliding amplitude determine the onset of motion and the transition from static to dynamic friction. This includes work on single- versus multi-asperity contacts and on pre-sliding behavior in stiff interfaces.
Friction and wear are coupled: sliding can create wear particles, modify surface roughness and change the chemistry of the interface. We investigate when wear accelerates frictional aging, when wear particles stabilize sliding, and how passivation species can suppress atom-by-atom material removal.
We explore strategies to tune interfacial forces, including humidity, water adsorption, surface chemistry, nanocrystal deposits and electric fields. The goal is to identify mechanisms that allow friction to be reduced, stabilized or switched on demand.
Experimentally, we use bespoke tribometers, optical contact visualization, AFM, surface characterization and controlled atmospheres. These methods allow us to relate measurable friction forces to contact geometry, surface evolution, local adhesion and interfacial chemistry. The resulting insights are relevant to nanolithography and more broadly to any technology where precise motion depends on predictable contact mechanics.
Group members
Bart Weber leads the Contact Dynamics group and holds an appointment as Associate Professor at the University of Amsterdam. His research focuses on various aspects of tribology: the science of friction, lubrication and wear.
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