The long march toward the zero friction

Abstract:
Friction causes massive energy dissipation and mechanical abrasion between machine component parts in the world every year (costing approximately 119 EJ). Understanding the mechanism of the frictional processes and searching for an optimum material combination, ideally providing a near frictionless state, are thus essential. Recent works show that near-zero interface friction can be realized in twisted 2D materials or 2D heterostructures due to their ultra-flat interface PES. However, the origin of friction is complex. Suppressing one primary source will make friction from other mechanisms to the surface. Thus, toward the pure zero friction state will be a long march.

The speaker will report the friction phenomenon of superlubric MoS₂/graphite and MoS₂/h-BN van der Waals heterostructure interfaces in this talk. Instead of reaching a frictionless state with a suppressed interface friction, in those interfaces, mechanisms like the edge pinning effect [1] and the variation of structure potential energy [2] start to dominate the friction processes and provide friction during the sliding and twisting. Those phenomena explain why it is hard to realize low friction on the macro scale. The speaker will also further discuss the main challenges and give possible ways toward a pure zero friction state in the talk.

References

[1] Liao, M., Nicolini, P., Du, L., . . . Zhang, G. (2022). UItra-low friction and edge-pinning effect in large-lattice-mismatch van der Waals heterostructures. Nature Material, 21(1), 47-53.

[2] Liao, M., Andrea, S., Du, L., . . . Zhang, G. (2022). The twisting dynamic of large lattice mismatch van der Waals heterostructures. Under review by Nature Communications.