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

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.