Frictional properties of self-adaptive chromium doped tungsten–sulfur–carbon coatings at nanoscale

Abstract

Transition metal dichalcogenides (TMD) are excellent dry lubricants forming thin (~ 10 nm) tribolayer that simultaneously protects the coating from environmental attack and provides low friction. In this paper, we focus on nanoscale frictional properties of chromium doped tungsten-sulfur-carbon (WSC-Cr) coatings with various Cr content. Friction force microscopy was used to investigate friction force as a function of load. A non-linear contact area dependence on the normal force was observed. The calculated interfacial shear strength was relatively low in the region of 70-99 MPa. Friction coefficient decreased with increased applied load independently of chromium content in the coatings.

First-principles comparative study on the interlayer adhesion and shear strength of transition-metal dichalcogenides and graphene

“…Indeed, in ultrahigh vacuum the performances of MoS 2 , the most common TMD, are superior to those of graphite [16], which on the contrary performs better in humid environments [17,18]. Furthermore, it was experimentally observed that TMDs can display lower friction coefficients when an external load is applied, at difference to most systems [19][20][21].…”

Nanotribological Investigation of Sliding Properties of Transition Metal Dichalcogenide Thin Film Coatings

“…Zekonyte et al 44,45 on W-S-C and W-S-C-Cr coatings. However, the probe shape can strongly influence the resulting contact properties.…”

“…First, we must note that some of the friction measurements with different probes of the same type followed the 2/3 power law (Supporting Information, Figure S4), thus indicating adhesive behavior according to the Hertz-plus offset model, similar to the previously reported results by Zekonyte et al , on W-S-C and W-S-C-Cr coatings. However, the probe shape can strongly influence the resulting contact properties .…”

“…The atomic force microscopy (AFM) probe mimics a single nanoscale asperity contact, thus offering a possibility for a wide array of nanotribological investigations. Friction force microscopy, which utilizes a measurement of lateral forces of the AFM probe in contact with the sample, has been previously successfully employed to study nano- and atomic-scale tribological properties of 2D materials: graphite, graphene, , exfoliated TMDs, , thin film TMD-based coatings, − or h-BN …”

Polymer brush lubrication of the silicon nitride–steel contact: a colloidal force microscopy study

“…32,33 The actual spring constant of the modied tip was calculated by internal built-in thermal noise methods. 34 Normal forces were calibrated by measuring the deection sensitivity (nm V À1 ) from the slope of the linear part of a force-displacement curve obtained on a at silicon surface. The normal force, F N , was set to zero at the point where the cantilever le the surface.…”