Tribometry and Instrumentation

In Situ Tribology

In situ studies are the state-of-the-art experiments for promoting a mechanistic understanding of complex systems through probing fundamental aspects of a system. Typically, interfacial interactions occur at an interface buried between two solids. This prevents access of traditional microscopy, spectroscopy and other analytical techniques to assess the interfacial interactions (including friction, wear and adhesion). In situ experiments afford the opportunity to make fundamental and mechanistic observations of complex systems (see publications for journal articles and presentations on in situ techniques).

State of the art in situ studies include in situ contacting, adhesion and sliding experiments using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS), electron backscatter diffraction (EBSD) to link material microstructure and its evolution during surface interactions.

In Situ surface interfacial chemistry can be achieved through in situ Raman and surface enhanced Raman spectroscopy (SERS). Molecular scale transfer of solid lubricant materials, including graphite and polymers can be measured after as early as one sliding cycle through in situ surface plasmon resonance (SPR) and surface enhanced Raman spectroscopy (SERS). In situ x-ray photoelectron spectroscopy (XPS) can be used to observe tribochemical changes at sliding interfaces to understand the dynamic, evolving nature of a sliding interface. It is hypothesized that tribochemical reactions occur in polymers, resulting in molecular interactions that are much stronger than what may be predicted by non-reactive simulations. These surface reactions form tribochemically generated transfer films, which dramatically alter the adhesion, friction and wear of the system. Characterization of these new surface chemistries can provide valuable feedback for theoreticians and computationalists doing MD simulations for tribology. A fundamental understanding of these mechanisms could dramatically improve design of materials and mechanical systems.

In Situ Optical Methods: Using in situ optical microscopy and interferometry, we can realize real contact area between randomly rough surfaces with µN force resolution nm scale positioning capabilities. These experiments are used to compare with models of elastomer contact mechanics with collaborator Bo N.J Person at IFF-Institute. Bo is the leading theorists in adhesion and friction of elastomers. This work could dramatically improve the understanding of soft materials such as elastomers and rubbers and significantly alter design strategies for systems like tires, that are responsible for a significant amount of energy loss in automobiles.

In situ Contact Area

Examples of in situ studies


Undergraduate Research Positions Available

Research Opportunities

Oportunity for hands on research experience.

Now Accepting Applications.

In the Tribology Laboratory, undergraduates will do experimental research focused on interfacial interactions of condensed matter. This includes studying the fundamental origins of friction, wear, surface deformation and adhesion on complex surfaces and materials ranging from cells to nanocomposites in environments ranging space to kilometers under water.

Active research includes analysis of materials that recently returned from the international space station, evaluating wear of dinosaur dental fossils, developing and patenting ultra-low wear polymer nanocomposites, studying and designing biocompatible and bio-inspired polymeric and hydrogel materials, and collaborating internationally on the physics of soft matter interactions. This research in tribology is at the intersection of mechanical engineering, materials science and surface physics.

Nanomechanical and Tribological Properties on Hadrosaurid Dinosaurs

Nanomechanical and Tribological Properties on Hadrosaurid

Prof. Greg Sawyer, Greg Erickson and Brandon Krick measured nanomechanical and tribological properties on hadrosaurid (duck-billed dinosaur) dental fossils from the American Museum of Natural History. Using custom instruments, we measured tissue hardness and wear rates that were preserved in the 65 million year old tooth. These properties are preserved in fossilized teeth because apatite mineral content is the major determinant of dental tissue hardness. Measured tissue wear rates were used to simulate the formation of hadrosaurid tooth chewing surfaces using a 3-D wear simulation. The simulation results in a surface profile nearly identical to a naturally worn hadrosaurid dental battery. The model revealed how each tissue (of differing wear rates) contributed to the formation of sophisticated slicing and grinding features in these reptiles tens of millions of years before mammals evolved analogous chewing capacity. This capacity to measure wear-relevant properties preserved in fossils provides a new route to study biomechanics throughout evolution. See Journal papers:
Science, October 5, 2012, pp.98-101.

Experiments back from the International Space Station

Space Tribometers and Samples back for analysis

Materials on the International Space Station Experiments Space Tribometerd

Materials on the International Space Station Experiments (MISSE) Space Tribometers were the first ever active tribometers directly exposed to the Low Earth Orbit Environment

The Tribology Laboratory at Lehigh University is under construction

The lab as of May 2013

The lab as of July, 3rd 2013

The main laboratory is located in Lehigh's Packard Laboratory.