Ultrastrong Carbon Thin Films from Diamond to Graphene under Extreme Conditions: Probing Atomic Scale Interfacial Mechanisms to Achieve Ultralow Friction and Wear
Technical Report,22 Sep 2015,21 Sep 2016
NATIONAL CHUNG CHENG UNIVERSITY SAN-HSING Taiwan
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The aim of this research is to gain fundamental understanding of how to achieve low friction and wear in ultra strong carbon-based materials. Experimentally, we use in situ nanotribometry that enables nanoscale visualization and quantification of atomic-level processes of sliding contacts inside the transmission electron microscope TEM. These experiments are in turn modelled computationally using molecular dynamics, allowing better understanding of the atomic-scale processes controlling friction and wear. In this study, the interfacial behaviorsincluding adhesion forces and tribological performances of diamond-like-carbon DLC and have been investigated. We find very consistent pull-in forces, indicating that adhesion before contact is dominated by van der Waals interactions. In contrast, large scatter in the pull-off forces is observed. However, they correlate to the average normal force applied during contact, suggesting atomic bonding is occurring at the interface. Construction of DLC computational models has begun, which aims to understand the atomistic mechanisms controlling the pull-in and pull-off. Our goal is to characterize and understand the atomic-scale mechanisms governing the tribological behavior of hard carbon materials during initial sliding contact, in order to understand what controls and enables the transition from high to low friction and wear. Developing this scientific insight is important to enable widespread usage of these materials to applications such as vibrating joints, contacting and sliding surfaces in micro- and nanoelectromechanical systems for sensors and actuators, joints in vacuum or anhydrous environments as found in the upper atmosphere and in outer space, and protective coatings for bearings, bushings, and gears in engines, turbines and other aerospace components.
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