Load-induced confinement activates diamond lubrication by water

Area of Science:

• Tribology
• Materials Science
• Surface Chemistry

Background:

• Tribochemical reactions occur at sliding interfaces, involving lubricants or environmental molecules.
• In situ monitoring of these reactions is challenging, hindering atomistic understanding and control.
• Understanding tribochemistry is crucial for designing advanced lubricants and materials.

Purpose of the Study:

• To provide a real-time atomistic description of tribochemical reactions between diamond films.
• To elucidate the role of nanoscale confinement in catalyzing these reactions.
• To understand how tribochemical reactions influence friction at the nanoscale.

Main Methods:

• Large-scale ab initio molecular dynamics simulations.
• Atomistic modeling of tribochemical reactions at diamond-diamond interfaces.
• Analysis of load-induced confinement effects on surface chemistry.

Main Results:

• Load-induced confinement catalyzes diamond passivation via water dissociative adsorption.
• Passivation lowers surface energy and increases electronic repulsion between contacting surfaces.
• High coverage of passivating species prevents surface sealing, leading to reduced friction.

Conclusions:

• Nanoscale confinement significantly impacts reaction kinetics and surface thermodynamics during tribochemical processes.
• Findings provide insights into friction reduction mechanisms at diamond interfaces.
• This study offers a foundation for designing novel lubricants and tribosystems.