Slip Sliding Away: Atomic-scale Processes That Govern Friction And Wear

Date: 
Monday, April 28, 2014
Location: 
1 LeConte Hall
Author/Speaker: 
Affiliation: 
Professor and Chair of Physics, University of Pennsylvania
Public Lecture: 
Yes
Name: 
Sarah Wittmer
Phone: 
(510) 642-3034
Webcast: 
Video Duration: 
67:43

I will discuss recent atomic force microscopy studies of nanoscale single asperity contacts. First, the frictional behavior of truly 2-dimensional materials will be discussed. For contacts to graphene and other 2-D materials, friction depends strongly on the number of 2-D layers. An even stronger effect occurs when graphene is fluorinated, an effect which can be interpreted in the context of the classical Prandti-Tomlinson model of stick-slip friction. I will then discuss the characterization of wear with unprecedented resolution using in-situ tests inside of a transmission electron microscope. For silicon slid against diamond, the shape evolution and volume loss due to wear closely fit a kinetic model based on stress-assisted bonding mechanisms. This allows new insights to be gained about the kinetics of atomic-scale wear.