Role of humidity in reducing sliding friction of multilayered graphene

Stiffness-dependent interlayer friction of graphene

“…The smoother motion of the flake on the incommensurate substrate leads to less energy dissipation [14,18,20,22,23], which is the reason why the friction force in the incommensurate case is substantially lower than that in the commensurate case. We note that the sp2 to sp3 transformation can initiate the transfer layer formation on the counterface and affect friction [34,51,52]. However, in the present simulations, no structural change (including sp2 to sp3 transformation, bond breaking, and rebonding) is observed.…”

“…These studies showed that the friction between graphene layers is significantly influenced by the normal load [16,21], commensurability [12-18, 22, 23], contact edge [21,[24][25][26][27], surface conditions [28][29][30][31][32][33], and environmental conditions such as humidity [34], etc. The friction force generally increases with increasing the normal load because it reduces the interfacial spacing and thus increases the interfacial shear resistance [16,21].…”

“…The surface conditions, such as defects [28,29], roughness [30] and morphology [31][32][33], may have strong effects on the interfacial interaction and thus have remarkable influence on the nanoscale friction. The interlayer friction coefficient of multilayer graphene decreases with the relative humidity of atmosphere, due to H and OH passivation of graphene [34].…”

Toward Robust Macroscale Superlubricity on Engineering Steel Substrate

“…[9][10][11][12][13] It is essential that an ideally rigid layerby-layer sliding structure with weak interaction remains atomically flat, molecularly clean, and structurally incommensurate so as to achieve structural superlubricity. [3,7,14] In a macroscopic sense, however, surface asperities have physical interlocking actions and thus affect the friction; and there inevitably are disordered structure, defect, chemical interaction, [15] adsorption, [16] and friction-induced damage [17] during the rubbing process of macroscale contact. In particular, there is often a large contact area at sliding interface and there are countless macroscale asperities on the contact surface, which makes it impracticable to maintain large-area incommensurate contact.…”

Friction and Wear Behaviour of Polyester Nanocomposites with Graphene Oxide and Graphite Investigated Through Block-on-ring Test

“…The decrease in the coefficient of friction could be caused by a reduction of the water layer on the sample and on the counter body [12,[15][16][17]. It is reported that increasing the relative humidity, the friction coefficient decreases and this is related to passivation of dangling bonds that form C-O, C-O-C and C-OH [18][19][20]. Friction can also be affected by different preparation methods [5,9,[21][22][23][24][25][26].It was found that the friction of graphene under interfacial friction condition has 60 0 periodicity, and the friction force along armchair orientation is larger than the friction force along zigzag orientation.…”