In dry sliding conditions, polytetrafluoroethylene (PTFE) composites can form thin, uniform, and protective transfer films on hard, metallic counterfaces that may play a significant role in friction and wear control. Qualitative characterizations of transfer film morphology, composition, and adhesion to the counterface suggest they are all good predictors of friction and, particularly, wear per...

We studied the layer-by-layer collapse of molecularly thin films of a model lubricant confined between two atomically smooth substrates. The dynamics of the consecutive expulsion of four molecular layers were found to slow down with decreasing film thickness but showed no evidence for confinement-induced solidification. Using a hydrodynamic model, we show that the sliding friction of liquid lay...

We report peculiar velocity quantization phenomena in the classical motion of an idealized 1D solid lubricant, consisting of a harmonic chain interposed between two periodic sliders. The ratio upsilon(c.m.)/upsilon(ext) of the chain center-of-mass velocity to the externally imposed relative velocity of the sliders stays pinned to exact "plateau" values for wide ranges of parameters, such as sli...

High-resolution electron microscopy imaging and electron and X-ray diffraction techniques have been used to characterize the structure of low and high flux Au-20%Pd layers in Au-20%Pd/MoS2 multilayer solid lubricant thin films. Images clearly reveal different morphologies for the metal layers in the two flux regimes, which can be correlated to the variation in fracture resistance reported by an...

The task of wear resistance improvement for bearing steels working at high loads in water medium was solved by laser alloying with Sn. The modified zone contains up t o 22 wt.% Sn, which is used as a solid lubricant during exploitation. As a result the bearing race's durability is increased 2.5 times. The combination of laser alloying from a nitrogen jet with surface plastic deformation (SPD) w...

The main objective of this work is to propose a mathematical model for the differential sticking coefficient of clayey drilling fluids with a lubricant as an additive and evaluate the influence of differential pressure and lubricant content on filter cake thickness and permeability. Tests were carried out on fluids composed of water and 4.86% of active bentonite clay prepared in Hamilton Beach ...

This paper aims to provide an understanding of the intrinsic frictional behaviour of CNTs under contact sliding by eliminating the possible effects of CNT rolling and slipping. Two critical steps towards the mechanism exploration were carried out: (1) the development of a new deposition method for CNT film fabrication, which allows the manufacture of densely packed, highly entangled CNT films t...