Dynamics of Self-retracting motion of graphite micro-flakes

TL;DR

This study investigates the self-retracting motion of graphite micro-flakes, revealing that the retracting speed is similar in air and vacuum, and analyzing the thermally activated sliding behavior through acceleration measurements.

Contribution

It provides comparative measurements of SRM speeds in different environments and characterizes the acceleration behavior, highlighting thermally activated processes in graphite micro-flakes.

Findings

SRM speed is nearly identical in air and vacuum environments.

Acceleration decreases linearly with log speed at high velocities.

Acceleration increases linearly with log speed at low velocities.

Abstract

A sheared microscopic graphite mesa retracts spontaneously to minimize interfacial energy. Using an optical knife-edge technique, we report comparative measurements of the speeds of such self-retracting motion (SRM) in air and low vacuum (about 1 Pa). We found that the retracting speed Vm of SRM is almost the same in the two environments at both room temperature and high temperature (above 150 celsius degree). We also extract the acceleration of the SRM, and found some typical behaviors. In the high speed range (above 5 m/s), the acceleration decreases linearly with the logarithm of the SRM speed. We attribute this phenomenon to the thermally activated sliding process in SRM. In the low speed region (between 0.1 m/s and 1 m/s), the acceleration increases linearly with the logarithm of the SRM speed.