Current Issue : July - September Volume : 2014 Issue Number : 3 Articles : 4 Articles
Interactions between surfaces are ubiquitous phenomena in living organisms.\nNature has developed sophisticated strategies for lubricating these systems, increasing their\nefficiency and life span. This includes the use of water-based lubricants, such as saliva and\nsynovial fluid. These fluids overcome the limitations of water as a lubricant by the\npresence of molecules such as proteins, lipids, and polysaccharides. Such molecules may\nalter surface interactions through different mechanisms. They can increase viscosity\nenabling fluid-film lubrication. Moreover, molecules adsorb on the surfaces providing\nmechanisms for boundary lubrication and preventing wear. The mentioned molecules have\ntypical sizes in the nanometer range. Their interaction, as well as the interaction with the\nentrapping surfaces, takes place through forces in the range of nanonewtons. It is therefore\nnot surprising that the investigation of these systems have been boosted by development of\ntechniques such as scanning probe microscopies and the surface force apparatus which\nallow studying tribological processes at the nanoscale. Indeed, these approaches have\ngenerated an enormous amount of studies over the last years. The aim of this review is to\nperform a critical analysis of the current stage of this research, with a main focus on studies\non synovial joints and the oral cavity....
This paper reviews the effects of lubricant additives and base stock used in\nmetal belt continuously variable transmissions (CVT) fluids on the CVT transmission\ntorque capacity. Additive formulation composed of phosphorus anti-wear agent, calcium\ndetergent, and dispersant improved the friction coefficient between the metals. The\nanalysis on the post-test surface suggests that the friction behavior strongly depends on the\nlocal morphology of the tribofilms derived from lubricant additives. Examining the effect\nof base stock on the torque capacity in actual belt CVTs revealed that SN (synthetic\nnaphthene) exhibited 10% higher torque capacity than that of PAO (polyalphaolefin). It is\nbelieved that the difference in the torque capacity is due to the difference in the oil-film\nshearing force generated by the relative sliding between the belt and pulley....
Phosphate esters, thiophosphate esters and metal thiophosphates have been used\nas lubricant additives for over 50 years. While their use has been extensive, a detailed\nknowledge of how they work has been a much more recent development. In this paper, the\nuse of phosphate esters and thiophosphate esters as anti-wear or extreme pressure additives\nis reviewed with an emphasis on their mechanism of action. The review includes the use of\nalkyl phosphates, triaryl phosphates and metal containing thiophosphate esters. The\nmechanisms of these materials interacting with a range of iron and steel based bearing\nmaterial are examined....
The article is devoted to modeling of the molecular microscopic journal bearing.\nThe walls and the lubricant of the bearing are fullerene-like molecules. On the basis of\nsimilarity theory and analysis of the dimensions, the similarity criterion is proposed. This\ncriterion characterizes the convergence of a numerical solution. The test calculation is also\nmade to evaluate the quality of the proposed criterion....
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