Generalized Scaling Law of Structural Superlubricity

Area of Science:

• Tribology
• Materials Science
• Nanotechnology

Background:

• Structural superlubricity enables ultralow friction via incommensurate interface force cancellation.
• Understanding friction scaling laws is key for macroscale superlubricity applications.
• Kinetic friction is a primary energy dissipation mechanism during sliding.

Purpose of the Study:

• To develop a general analytical theory for the scaling law of structural superlubricity.
• To explain nanoscale experimental measurements of friction scaling.
• To validate the theory on the microscale and predict scaling behavior at larger sizes.

Main Methods:

• Extensive molecular dynamics simulations.
• Development of an analytical general theory for friction scaling.
• Experimental validation using microscale superlubric graphite/hexagonal boron nitride heterojunctions.

Main Results:

• An analytical theory for structural superlubricity friction scaling was introduced.
• The theory successfully explains existing nanoscale experimental data.
• Microscale experiments validated the theory, revealing a characteristic size D ≈ 100 nm for scaling transition.

Conclusions:

• The proposed theory provides fundamental insights into friction origins in structural superlubricity.
• A transition from sublinear to linear friction scaling is predicted above a characteristic size.
• The findings are beneficial for advancing macroscale applications of superlubricity.