Ultralow Macroscale Friction and Wear of MoS₂ in High‐Vacuum Through DC Pulsing Optimization, Nitridization, and Sublayer Engineering

Abstract

The reliability and durability of devices that operate in vacuum and are subjected to wear are critical issues. The concerns rise at the macroscale wherein the contact area is large, yet the contact stress is in the GPa range. This paper reports on the design and fabrication of a coating comprising nitridized molybdenum disulfide (MoSN) supported by a novel nanolayered coating composed of carbon with subnanometer‐thick periodic albeit discrete Cr interlayers. The MoSN coatings are deposited onto mating surfaces using pulsed‐DC magnetron sputtering in an atmosphere with varying N2 to argon (Ar) ratios. Pulsed‐DC parameters, such as pulse duty and frequency, together with nitrogen content, are systematically optimized to achieve superior mechanical and tribological properties. The results reveal the importance of optimizing pulsing parameters during deposition as they significantly alter the properties of MoS2. The outcome is fabrication of a coating that despite having a low thickness, exhibits extremely low friction and record‐breaking macroscale wear rate in high vacuum compared to the values reported in the literature by date. Lastly, the analysis confirms the prediction of theoretical studies regarding the release of entrapped nitrogen in gaseous form during the wear process without disrupting the formation of a stable solid lubricant tribofilm.

A Systematic Review of the Recent Advances in Superlubricity Research

“…In-depth research by scholars from various countries has made great progress, solid superlubricity and liquid superlubricity materials have been widely tapped, and many emerging materials have also joined the study of superlubricity, such as black phosphorus, the Mxenes family, etc. ; many classical superlubricity materials have also been explored and new systems have been developed; and high-temperature superlubricity and solid-liquid combined superlubricity have also achieved very significant research results [197][198][199][200][201]. In this article, we introduce the origin and concept of superlubricity to give readers a clear understanding of the importance of superlubricity; categorize and overview the domestic and international research progress of superlubricity; and explore the generation mechanism of various types of superlubricity in the hope of discovering universally applicable mechanisms from a wide range of superlubricity designs.…”

Dual in-situ observation of tribochemical and morphological evolution of single-layer WS2 and multi-layer WS2/C coatings

“…Therefore, a lot of research and development has been done on solid lubricant materials to enhance friction reduction and anti-wear performance, boosting the reliability and effectiveness of tribological systems [4,5]. The remarkable lubricating characteristics of transition metal dichalcogenides (TMDs) in high vacuum and high temperature settings have led to their emergence as representative solid lubricants and their widespread application in the field of space engineering during the past several decades [6][7][8][9][10]. The superior tribological properties of TMDs stem from their unique structure [11][12][13][14].…”