Angular dependence of nanofriction of mono- and few-layer MoSe2

Effect of the crystallographic c-axis orientation on the tribological properties of the few-layer PtSe2

“…From the friction force dependence on the applied load (Fig. 6b), we can also estimate the COF of the prepared films by comparing the slope of the fits that of the reference sapphire substrate sample with known values of COF [8]. COFs measured by this way are also listed in Table 2.…”

“…The layered crystals, self-assembled monolayers, and hard amorphous and crystalline coatings [7][8][9][10] were proposed as effective thin-film materials to reduce friction and wear of the individual elements of the low-dimensional systems. Van der Waals (vdW) twodimensional (2D) layered crystals with a thickness of several atomic layers and extended dimensions in the other two directions became the most popular dry lubricant, owing to the low shear force between their layers [10,11].…”

“…There are over 40 different combinations of chalcogen and transition metal atoms [14]. Besides many applications of 3 TMD, including gas sensing, field-effect transistors, energy storage, photodetectors, and catalysis [15][16][17][18][19], these materials have also attracted attention in the tribological studies [8,10]. Similar to graphene [20], they are characterized by atomic flatness, high in-plane mechanical strength, and chemical versatility [21].…”

“…However, a deeper understanding of the friction mechanisms for other 2D material coatings in the widely extended network of layered crystals is still limited [21]. In particular, effects of the surface forces, crystallographic orientation and anisotropy of mechanical properties need to be considered [2,8,10]. A frictional anisotropy of layered crystals attracts attention for a long time due to the difference in the mechanical properties of the crystals in directions parallel and perpendicular to their basal plane [2].…”

Nanofriction Properties of Mono- and Double-Layer Ti3C2Tx MXenes

“…3 Two-dimensional (2D) materials with a thickness of several atomic layers while extending in the other two dimensions exhibit outstanding friction effects such as superlubricity, stick-slip, puckering, friction hysteresis, or directional anisotropy. 4,5 Excellent tribological and mechanical properties of graphene have been demonstrated and attracted great interest in the frictional properties of other 2D materials, especially for dry lubrication at the nanoscale. 6−8 Thus, technologically unique 2D materials with superior strength and high thermal stability, such as graphene and transitional metal dichalcogenides (TMD) as well as recently proposed talc, are being used as customizable single-component dry lubricants.…”