Tribology studies the science and technology of surfaces in relative motion. It includes the principles of:
Tribology is derived from the Greek word “tribo,” which means “rub.”
The focus of this research is to learn about the physics at an interface using a tribological system as the tool. The aim is to understand what occurs at a sliding interface, that is:
•Bonds (breaking, forming)
The research also seeks to find what wear mechanisms are responsible across different regimes in parameter space; to understand the origins of the extreme tribological properties of carbon-based films:
–Ultralow friction & wear
Novel carbon films have several potential applications:
Micro- and nano-devices need to be made from new materials to overcome tribological challenges:
–Thermomechanical data storage
–Wear of AFM tips for extended imaging periods, nanofabrication, nanolithography.
Aims of Project:
Learn about the physics at an interface using a tribological system as the tool; understand what occurs at a sliding interface (bonds breaking/ forming and temperature changes).
-Find what wear mechanisms are responsible across different regimes in parameter space
To understand the origins of the extreme tribological properties of carbon-based films (Ultralow friction & wear; Low adhesion). These films have a number of potential applications.
Carbon possesses properties that make it an attractive material:
–Ultralow friction & wear
Ultrananocrystalline diamond (UNCD) has a low coefficient of friction and low wear rate, but only at sufficiently high relative humidity.
Background: (Grierson et al, “Origin of Ultralow Friction and Wear in Ultrananocrystalline Diamond,” American Physical Society, Peer Review Letters, PRL 100, 235502 (2008)).
The impressively low friction and wear of diamond in humid environments is debated to originate from either the stability of the passivated diamond surface or sliding-induced graphitization/rehybridization of carbon.
Ultralow friction and wear for ultrananocrystalline diamond (UNCD) surfaces was found even in dry environments, and negligible rehybridization observed except for a modest, submonolayer amount under the most severe conditions (high load, low humidity).
This supports the passivation hypothesis, and establishes a new regime of exceptionally low friction and wear for diamond.
The remarkably low friction and wear of diamond, particularly in humid environments, is postulated to be due to either rehybridization, or passivation of dangling bonds formed during sliding.
• Self-mated reciprocating wear of UNCD in varied relative humidity (RH) environments
– Four tracks made
– Examine behavior in different wear regimes
• Post-wear characterization of tracks
• Compare mechanics and chemistry of worn versus unworn surfaces
Major experimental steps:
- X-ray Absorption Near-Edge Spectroscopy (XANES).
- PhotoElectron Emission SpectroMicroscopy (PEEM)
- Raman Spectroscopy.