Search

Tribological properties of acid and alkali solutions on glass surface were studied in aqueous environment using a ball-on-disc reciprocating configuration. Interactions between lubricants and sliding surfaces produce different surface topographies. The lubricating ability of each kind of surface topography was evaluated using the same base oil. Wear tracks which were smooth or with grooves on the surfaces had high coefficient of friction in reciprocating sliding tests. However, surfaces with pits exhibited much lower friction than that the others. Low friction coefficients could be achieved after the running-in process with acidic solutions, accompanied by the formation of a pitted topography on the wear tracks. Especially, the friction coefficient was found to be below 0.01 during the steady sliding period, except at the reversal positions. Such good lubricity could be attributed to the micro-sized pits. [ABSTRACT FROM AUTHOR]

The contact and friction behavior of a medical compression stocking (MCS) under different strains was investigated in friction and compression experiments against a mechanical skin model. In addition, the 3D topography of the MCS surfaces was analyzed in order to study the relationship between macroscopic friction and microscopic surface properties. The load dependence of friction coefficients was found to be in accordance with the adhesion friction model. The surface structure of MCS samples was considerably changed when varying the strain state, while friction coefficients remained comparable, indicating real contact areas independent of strain on the microscopic level. The experimental findings could be confirmed and explained on the basis of the microscopic surface analyses, when interpreting the fabric surfaces to be composed of numerous individual round asperities obeying the Hertz contact model. [ABSTRACT FROM AUTHOR]

The work reported in this paper aims at understanding sliding friction anisotropy at the nano-, micro-, and macroscales with respect to surface asperity orientation and exploring the mechanisms behind this phenomenon. Experiments were conducted by probing surfaces with grooves parallel or perpendicular to the direction of relative motion. Continuum mechanics analyses with the FEM and a semi-analytical static friction model and the atomic molecular dynamics simulation were performed for the mechanism exploration. Friction anisotropy was understood from the differences in contact area, surface stiffness, stiction length, and energy barrier from the continuum mechanics prospective and from that in the stick-slip phenomena at the atomic level. [ABSTRACT FROM AUTHOR]

Tribological properties of Si/Si contacts were measured on a microscale by using an atomic force/friction force microscope. Friction forces and pull-off forces between a Si tip and a polished surface of a Si(100) wafer were studied as a function of applied normal load and relative humidity of the surrounding air. The results show that pull-off forces and friction coefficients increased and were strongly influenced by capillary forces with increasing humidity. Tribological interactions during 20 passes of overlapping sliding contact at 50% relative humidity and very small loads of 70 nN were confined to the layer of adsorbates and chemical reactions, without measurable solid damage on the Si(100) wafer. [ABSTRACT FROM AUTHOR]