Structural Superlubricity at High Sliding Speeds under Ambient Conditions

TL;DR

This study demonstrates that structural superlubricity persists at high sliding speeds over 100,000 nm/s under ambient conditions, showing minimal friction increase, which is promising for practical superlubric devices.

Contribution

It provides experimental evidence that superlubricity can be maintained at high speeds, addressing a key limitation for real-world applications.

Findings

Superlubricity extends over 100,000 nm/s with minimal friction change.

Friction signals can be detected at extremely low levels using heterodyne detection.

The superlubric regime remains stable across three orders of magnitude in speed.

Abstract

Structural superlubricity is an intriguing physical phenomenon, whereby sliding at a structurally incommensurate, atomically flat interface yields vanishingly small friction forces. Despite its recent experimental validation, critical questions remain regarding the physical limitations of the concept. In particular, it is not known whether the ultra-low friction state would persist at high sliding speeds relevant for practical, small-scale mechanical systems. Here, we perform sliding experiments via atomic force microscopy on gold nanoislands on graphite at increasing speeds, extracting interfacial friction forces under ambient conditions. A heterodyne detection methodology enables the extraction of extremely weak friction signals buried deep in the noise, revealing that the structurally superlubric regime extends over 100,000 nm/s with minimal changes in friction force, spanning three orders of magnitude in sliding speed. Our results contribute significantly to the pursuit of functional, superlubric mechanical devices.