Synthesis and Tribological Performance of Novel Mo x W1−x S2 (0 ≤ x ≤ 1) Inorganic Fullerenes

Abstract

Inorganic fullerene-like (IF) MoS 2 and WS 2 nanoparticles were found to be good friction modifiers and anti-wear additives when dispersed in a lubricant. Their tribological performance seems to be related to the structure, size, and shape of these nanomaterials. The present study describes the tribological properties of a new inorganic fullerene IF-Mo x W 1-x S 2 containing both molybdenum and tungsten disulfide under boundary lubrication. Mo x W 1-x S 2 amorphous inorganic fullerene nanostructures were synthesized by means of MOCVD using an induction furnace setup. The average diameters range from 25 to 45 nm. Upon variation of the amounts of precursors and S, various solid solutions of IF-Mo x W 1-x S 2 were obtained. In addition, a morphological, chemical, and structural analysis of the samples was performed using high resolution scanning electron microscopy (HRSEM), transmission electron microscopy (TEM), and X-ray powder diffraction (XRD). Friction experiments were carried out with a ball-on-flat contact using an environmental tribometer. The results show interesting friction reducing and wear properties of these nanomaterials. The change in the molecule stoichiometry, which led to a variation of particles size but also to a variation of the crystallinity of the particles, affects the tribological performance.

Understanding the Tribochemical Mechanisms of IF-MoS2 Nanoparticles Under Boundary Lubrication

“…Recently, Tenne and co-workers [7] suggested that an additional rolling process for well-crystallized and round-shaped particles could enhance the lubricating properties of the IF nanoparticles. A recent trend in the synthesis of the fullerenes is to prepare faulted and strained IF nanostructures to facilitate their exfoliation in the tribological contact and thus to optimize the tribological properties of the lubricant [8]. Recently, some metal-doped fullerenes were also prepared [9,10].…”

Real Time TEM Imaging of Compression and Shear of Single Fullerene-Like MoS2 Nanoparticle

“…This mechanism called as ''drug delivery mechanism'' by the authors is extremely interesting because the lubrication additive is brought directly inside the contact area without any prior chemical reaction, explaining the reason why IF particles are efficient starting from the first cycle of the test and at ambient temperature. Concerning the IF nanoparticles, it has recently been shown that the shape, structure (degree of crystallinity and number of defects) and size of the nanoparticles strongly affect their lubricating performances [12,13]. For example, Tannous et al [12] showed that small and poorly crystallized fullerenes of MoS 2 are much more efficient than the well-crystallized ones.…”

“…Concerning the IF nanoparticles, it has recently been shown that the shape, structure (degree of crystallinity and number of defects) and size of the nanoparticles strongly affect their lubricating performances [12,13]. For example, Tannous et al [12] showed that small and poorly crystallized fullerenes of MoS 2 are much more efficient than the well-crystallized ones. The author concluded that, with fullerenes exceedingly discontinuous in their layers, exfoliation process could be enhanced by the large number of defects present in the particles.…”

High Lubricity of Re-Doped Fullerene-Like MoS2 Nanoparticles

“…They were shown to exhibit very good tribological behavior with numerous potential applications, like additives to lubricating fluids [2,3]; as selflubricating coatings [4] and for improving the mechanical behavior of nanocomposites [5,6]. Indeed products based on these new nanomaterials have already been commercialized.…”