The objective of this research is to understand the phenomenon of atomic stick-slip friction, including the newly discovered transition to stable sliding with ultralow energy dissipation. The research will be conducted through a closely-coordinated experimental and modeling effort. The experiments will use advanced atomic force microscopy (AFM) with well-defined samples and tips to measure atomic-scale friction. This will be synergistically coupled to an atomistic modeling effort that will employ physically representative potential models and accelerated molecular dynamics (MD) to match the time scale of the experiments. This research will provide an understanding of atomic-scale friction and energy dissipation at a new level of insight. It will also help to provide new, fundamental, and widely applicable principles that govern the sliding motion of nanoscale devices such as nano-electromechanical systems (NEMS) and ultrahigh density probe-based data storage devices. The project will leverage highly effective educational outreach programs at both Purdue University and the University of Pennsylvania. Specific priorities include hosting ?research experience for teachers? fellows, development of multi-purpose demonstration modules based on AFM, and active participation in international collaborative cyber-network communities.

Project Report

Friction is found in every-day life and has significant effects in machinery, manufacturing, and transportation. Studying friction at small scales helps us understand how friction originates and helps us to develop the knowledge we need to control and, if desired, minimize friction. The objective of this research was to understand the phenomenon of atomic stick-slip friction. This behavior, where a contact point slides one atomic position at a time across a surface, has been observed for many years but not yet understood. The intellectual merit of this work was to show that the speed dependence of atomic stick-slip friction observed in experiments could be predicted by atomic simulations. This is important because it means that such simulations can potentially be used to predict friction in other cases. However, the agreement was not perfect, as there was one difference which was due to the much larger mass (larger size) of the overall experiment compared to the simulation. However, knowing this, corrections can be made to such simulations in the future so that they can be properly conducted and interpreted. The broader impact of this work is to provide an understanding of atomic-scale friction and energy dissipation at a new level of insight. It also helps to provide new, fundamental, and widely applicable principles that govern the sliding motion of nanoscale devices such as nano-electromechanical systems (NEMS) and ultrahigh density probe-based data storage devices. The project leveraged highly effective educational outreach programs at both Purdue University and the University of Pennsylvania. Specific priorities include hosting a high school teacher in the PI’s lab, developing a science demonstration module based on AFM, and active participation in public and K-12 "materials day" expos.

Project Start
Project End
Budget Start
2008-06-15
Budget End
2011-11-30
Support Year
Fiscal Year
2008
Total Cost
$213,684
Indirect Cost
Name
University of Pennsylvania
Department
Type
DUNS #
City
Philadelphia
State
PA
Country
United States
Zip Code
19104