Macroscale Superlubricity Accomplished by Sb₂O₃-MSH/C Under High Temperature

Area of Science:

• Materials Science
• Tribology
• Surface Engineering

Background:

• Superlubricity is a state of extremely low friction, crucial for reducing wear and energy loss in mechanical systems.
• Achieving superlubricity at high temperatures remains a significant challenge, limiting applications in demanding environments.
• Nickel superalloys are vital in high-temperature applications but suffer from friction and wear issues.

Purpose of the Study:

• To develop and investigate a novel coating for achieving high-temperature superlubricity on nickel superalloy substrates.
• To elucidate the tribological mechanisms responsible for superlubricity under elevated temperatures.
• To evaluate the protective and lubricating properties of the developed coating system.

Main Methods:

• Coating deposition via burnishing antimony trioxide (Sb₂O₃) and carbon-coated magnesium silicate hydroxide (MSH/C) powders onto a nickel superalloy.
• Tribological testing in an open-air environment across a range of temperatures.
• Surface analysis using in-situ Raman spectroscopy, cross-sectional transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS).

Main Results:

• The coating exhibited a decreasing coefficient of friction (COF) with increasing temperature, reaching superlubricity (COF = 0.008) at 300°C.
• Synergistic effects between the Sb₂O₃ adhesion layer and the MSH/C top layer protected the substrate from sliding and oxidation.
• Tribochemically activated formation of an amorphous carbon layer on the coating surface was observed via TEM and XPS.

Conclusions:

• The developed Sb₂O₃/MSH/C coating enables macroscale superlubricity at high temperatures.
• The synergistic action of the coating layers and the formation of a protective amorphous carbon film are key to achieving this phenomenon.
• This research offers a promising solution for reducing friction and wear in high-temperature applications involving nickel superalloys.