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Simulating Fullerene Ball Bearings of Ultra-low Friction

Xiaoyan Li's picture

We report the direct molecular dynamics simulations for molecular ball bearings composed of fullerene molecules (C60 and C20) and multi-walled carbon nanotubes. The comparison of friction levels indicates that fullerene ball bearings have extremely low friction (with minimal frictional forces of  5.283×10-7 nN/atom and  6.768×10-7 nN/atom  for C60 and C20 bearings) and energy dissipation (lowest dissipation per cycle of  0.013 meV/atom  and  0.016 meV/atom  for C60 and C20 bearings). A single fullerene inside the ball bearings exhibits various motion statuses of mixed translation and rotation. The influences of the shaft's distortion on the long-ranged potential energy and normal force are discussed. The phonic dissipation mechanism leads to a non-monotonic function between the friction and the load rate for the molecular bearings.

Paper published in the journal of Nanotechnology

Frictional coefficients of three molecular bearings


Henry Tan's picture

In the end of the paper it is written that for a molecular bearing at the atomic scale, the phononic excitation is a main energy dissipation mechanism.

Why the energy dissipation caused by the electronic excitation is not important?

Xiaoyan Li's picture

Thank you very much for your interest in our studies.
The friction at the nanoscale is controlled by two mechanisms: the electronic and phonon dissipations. Since to date, it is not clear which contribution of the phonons and electros to friction is dominant. Some researchers concluded that electronic and phonon dissipation channels are of similar importance for the microscopic origin of friction.
In our present investigation, we performed the classical molecular dynamics simulations which are unable to describe electronic motion and electronic structure in the bearings. Therefore, the contribution of phonon to friction is only studied, and the electron contribution is not considered.

This is a great blog showing the Simulation of Fullerene Ball Bearings. What is used in the DWCNTs bearing to cause its Frictional Coefficient of Bearing to rise so high? I use ball bearings from Acer Racing and want to know which one to use to get the most output from at the lowest cost, Thanks.

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