Fullerene‐like WS₂ Nanoparticles: Superior Lubricants for Harsh Conditions

Abstract

WS2 nanoparticles with closed‐cage structure (fullerene‐like IF) are already being synthesized in macroscopic amounts from the respective oxide nanoparticles. They have been studied as superior solid lubricants under harsh conditions in recent years. Under severe contact conditions both fluids and greases are squeezed out from the contact area and consequently do not provide adequate lubrication conditions. Addition of even a small amount of IF nanoparticles to the oil was found to reduce the friction coefficient and wear rate, and increase the load‐bearing capacity of the friction pairs. Furthermore, IF nanoparticles were impregnated into polymer and metal coatings and into self‐lubricating porous metal parts, and were found to alleviate both friction and wear remarkably well. In another set of experiments, IF nanoparticles were shown to provide excellent tribological behavior for the contact between a ceramic alumina block and silicon nitride ball.The mechanism for the impro ved tribological behavior of the IF nanoparticles is being investigated. In addition to the rolling friction, gradual exfoliation of the IF onions and transfer of monomolecular WS2 sheets onto the metal surface (third body transfer) is shown to play a major role in alleviating friction and wear. This work suggests numerous applications for this new solid‐state nanolubricant.

Nanocomposite biomaterials based on poly(ether-ether-ketone) (PEEK) and WS2 inorganic nanotubes

“…The coefficient of friction reaches its lowest value of around 0.21, a 44% drop, at 1.0 wt% loading, due to the enhanced mechanical performance combined with the lubricant effect of these nanotubes. Rapoport et al 52 have proposed a rolling mechanism for inorganic fullerene-like nanollers in which they act as a type of ball-bearing component, meaning that they roll rather than slide between the surfaces, effectively reducing the shear stress, coefficient of friction and contact temperature. A similar decreasing trend in m has been reported upon addition of other inorganic nanoparticles such as ZrO 2 , SiC or Si 3 N 4 to PEEK, whilst the incorporation of TiO 2 , CuO or SiO 2 led to similar or even higher values than the neat polymer.…”

Innovative biofilm inhibition and anti-microbial behavior of molybdenum sulfide nanostructures generated by microwave-assisted solvothermal route

“…It forms sandwich interlayer structure created by S-Mo-S layers, which are loosely bound to each other only by van der Waals forces (Rapoport et al 2005). Such structures, at the bulk and nanoscale, exhibit a broad array of applications, such as electrochemical hydrogen storage (Chen et al 2001), cathode material for rechargeable lithium batteries and solar cells (Imanishi et al 1992;Thomalla and Tributsch 2006), electric transport (Kopnov et al 2006), useful solid lubricant (Rapoport et al 2003), an intercalation host (Aharon et al 2006), and field emission tips (Nemanic et al 2003). For example, molybdenum disulfide may be an alternative material for next-generation nanoelectronic devices viz., transistor (Radisavljevic et al 2011) and tandem photovoltaic configurations because its electronic properties are superior to silicon (Li et al 2005) and its band gap transforms from indirect to direct at nanoscale.…”

Interlayer commensurability and superlubricity in rigid layered materials

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] This important characteristic has its origin in their nanoscopic anisotropic crystal structure consisting of strong covalent intra-layer bonding and weaker dispersive interlayer interactions. 15 One important consequence of this unique structure is the fact that the layers may slide on top of each other while overcoming relatively small energetic barriers.…”