Se Nanopowder Conversion into Lubricious 2D Selenide Layers by Tribochemical Reactions

Area of Science:

• Materials Science
• Tribology
• Nanotechnology

Background:

• Transition metal dichalcogenide (TMD) coatings are vital for tribological applications.
• Molybdenum disulfide (MoS2) is a common example, but selenides and tellurides offer superior properties.
• Existing TMD synthesis methods face challenges with stability and environmental degradation.

Purpose of the Study:

• To develop an in operando method for synthesizing 2D selenides from selenium nanopowders.
• To investigate the tribochemical formation and lubricating properties of these in situ generated selenides.
• To understand the atomistic mechanisms behind shear-induced selenide monolayer formation.

Main Methods:

• Sprinkling selenium nanopowders onto sliding metallic surfaces (Mo and W thin films).
• Advanced material characterization to analyze the formed tribofilm.
• Ab initio molecular dynamics simulations under tribological conditions.

Main Results:

• Successful tribochemical conversion of Se nanopowders into lubricious 2D selenides.
• Significant reduction in the coefficient of friction to below 0.1 in ambient air.
• Demonstration of thermal stability and prevention of outgassing in vacuum environments.
• Highly reproducible results due to the reactivity of Se nanopowder with metal coatings.

Conclusions:

• The in operando synthesis of 2D selenides offers a promising, straightforward approach for advanced solid lubrication.
• This method overcomes the limitations of traditional TMD lubricity degradation caused by environmental factors.
• The technique is suitable for replenishing solid lubricants on sliding components, enhancing durability and performance.