Diamond-Like Carbon: A Surface for Extreme, High-Wear Environments

Area of Science:

• Materials Science
• Surface Chemistry
• Tribology

Background:

• Diamond-like carbon (DLC) films are advanced coatings used in various applications.
• Understanding surface properties and interactions is crucial for optimizing DLC performance.
• The role of surface chemistry in antiwear mechanisms requires detailed investigation.

Purpose of the Study:

• To comprehensively characterize the structure and chemistry of a DLC film.
• To investigate the DLC surface and interface properties with air and liquid.
• To understand the adsorption behavior of a model surfactant on DLC surfaces.

Main Methods:

• In-depth characterization using multiple techniques.
• Analysis of DLC film interior, DLC/air surface, and DLC/liquid interface.
• Quartz-Crystal Microbalance (QCM) and neutron reflectivity for adsorption studies.

Main Results:

• DLC film composed of sp2 and sp3 carbon with surface oxygen (OH groups), indicating hydrophilicity.
• Significant adsorption of bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT) surfactant from aqueous solutions.
• Adsorbed surfactant forms a bilayer structure on the DLC surface.

Conclusions:

• The hydrophilic nature of the DLC surface influences additive interactions.
• The observed AOT bilayer adsorption provides insights into antiwear mechanisms.
• This study lays the groundwork for designing effective DLC-based antiwear systems.