Velocity-Dependent Friction of Graphene at Electrical Contact Interfaces

Area of Science:

• Materials Science
• Tribology
• Nanotechnology

Background:

• Graphene shows promise as a solid lubricant for micro-/nanoelectromechanical systems (MEMS/NEMS).
• Severe wear is a critical issue in sliding electrical contacts within MEMS/NEMS devices.

Purpose of the Study:

• To investigate the velocity-dependent friction of graphene under varying applied voltages.
• To understand how applied voltage influences graphene's tribological behavior in electrical contacts.

Main Methods:

• Friction measurements using conductive atomic force microscopy (c-AFM).
• Analysis using the Prandtl-Tomlinson model.
• Characterization of tip wear via SEM and adhesion measurements.

Main Results:

• At low voltages, graphene friction increases logarithmically with sliding velocity, accelerated by voltage.
• At high voltages, friction decreases with sliding velocity due to Joule heating and tip wear.
• Tip wear is more severe at lower sliding velocities under high voltage.

Conclusions:

• Applied voltage significantly alters graphene's friction behavior, influenced by thermal effects and tip wear.
• Joule heating under high voltage weakens the tip, increasing friction and wear.
• Optimizing sliding velocity is crucial for managing wear and friction in graphene-based electrical contacts.