Macro- to Nanoscale Wear Prevention via Molecular Adsorption

TLDR

As mechanical systems shrink from macro‑ to nanoscale, surface phenomena such as adhesion, friction, and wear become increasingly significant. The study demonstrates that alcohol adsorption can continuously replenish the lubricating layer on device surfaces and investigates the tribochemical reaction products formed during sliding contact. The authors examined friction and wear of native silicon oxide across macro‑, micro‑, and nanoscale devices using ball‑on‑flat, MEMS, and AFM tribometers while applying alcohol vapor to replenish lubrication. Alcohol vapor adsorption lubricated and prevented wear at all scales, producing high‑molecular‑weight oligomeric tribochemical products that enhanced lubrication and dramatically increased MEMS device lifetime.

Abstract

As the size of mechanical systems shrinks from macro- to nanoscales, surface phenomena such as adhesion, friction, and wear become increasingly significant. This paper demonstrates the use of alcohol adsorption as a means of continuously replenishing the lubricating layer on the working device surfaces and elucidates the tribochemical reaction products formed in the sliding contact region. Friction and wear of native silicon oxide were studied over a wide range of length scales from macro- to nanoscales using a ball-on-flat tribometer (millimeter scale), sidewall microelectromechanical system (MEMS) tribometer (micrometer scale), and atomic force microscopy (nanometer scale). In all cases, the alcohol vapor adsorption successfully lubricated and prevented wear. Imaging time-of-flight secondary ion mass spectrometry analysis of the sliding contact region revealed that high molecular weight oligomeric species were formed via tribochemical reactions of the adsorbed linear alcohol molecules. These tribochemical products seemed to enhance the lubrication and wear prevention. In the case of sidewall MEMS tests, the lifetime of the MEMS device was radically increased via vapor-phase lubrication with alcohol.