The structural, tribological, and rheological dependency of thin hexadecane film confined between iron and iron oxide surfaces under sliding conditions

On the effect of confined fluid molecular structure on nonequilibrium phase behaviour and friction

“…This type of behaviour is commonly observed in experiments and NEMD simulations of lubricants under EHL conditions. [1][2][3]66 Interestingly, the slope of the friction coefficient with log(strain rate) decreases with increasing pressure, as has been observed in NEMD simulations of binary Lennard-Jones mixtures. 2 Similar observations have also been made in recent NEMD simulations of n-hexadecane confined between a-Fe 2 O 3 slabs at high pressure.…”

“…35 This behaviour has been consistently observed in previous experiments and NEMD simulations of lubricants. [1][2][3]66 At the highest pressures considered (41.5 GPa), there is a sharp increase in experimentally measured shear stress with log(strain rate) at low strain rates (o10 5 s À1 ), due to viscoelastic accommodation of strain by the surface in the entry zone of the contact, in response to the very steep friction increase in this region. 3,69 However, at higher strain rates (410 5 s À1 ), the experimental shear stress shows the same linear increase with log(strain rate) as observed at lower pressure.…”

“…2 Similar observations have also been made in recent NEMD simulations of n-hexadecane confined between a-Fe 2 O 3 slabs at high pressure. 66 Consequently, the friction coefficient at 0.5 GPa exceeds that at 2.0 GPa at very high strain rates (42 Â 10 9 s À1 ).…”

“…The shear stress in the NEMD simulations was monitored through the mean lateral (friction) force acting on the outer layer of atoms in the top and bottom slabs in response to the fluid. 53,66 Fig . 4 shows the variation in the mean shear stress with log(strain rate) for the lubricants (squalane, DEHS) and traction fluids (DM2H, DCMP) at 80 1C, under several applied mean pressures.…”

Influence of molecular structure on lubrication of aqueous triblock copolymer lubricants between rutile surfaces: An MD approach

“…The solution was initially prepared by assigning a thin layer of copolymer molecules (Table 1) sandwiched between water layers. The simulation, which was similar to previous research by the authors, includes three stages [34,37,38]. (I) Firstly, the rigid layers were fixed and an NVE ensemble was applied to them, while the remains of surface were free and thermostated at 300 K by Nose-Hoover NVT ensemble.…”