Friction and Lubricity

Frictional effects of PDMS sliding on gold surfaces,glass, silicon oxide surfaces, or glassy polymers, have been investigated in detail. There has also been some interest in self-lubricating biomaterials. - 

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F. P. Bowden and D. Tabor, The Friction and Lubrication of Solids, The Clarendon Press, Oxford, 1950. 

This chapter and the two that follow are introduced at this time to illustrate some of the many extensive areas in which there are important applications of surface chemistry. Friction and lubrication as topics properly deserve mention in a textbook on surface chemistiy, partly because these subjects do involve surfaces directly and partly because many aspects of lubrication depend on the properties of surface films. The subject of adhesion is treated briefly in this chapter mainly because it, too, depends greatly on the behavior of surface films at a solid interface and also because friction and adhesion have some interrelations. Studies of the interaction between two solid surfaces, with or without an intervening liquid phase, have been stimulated in recent years by the development of equipment capable of the direct measurement of the forces between macroscopic bodies. 

Bowden F P and Tabor D 1964 Friction and Lubrication of Soiids Part II (Oxford Oxford University Press)... 

Yoshizawa H, Chen Y L and Israelachvili J N 1993 Recent advances in molecular level understanding of adhesion, friction and lubrication Wear 6B 161-6... 

Other fields of surface study were of course developing the study of catalysts for the chemical industry and the study of friction and lubrication of solid surfaces were two such fields. But in sheer terms of economic weight, solid-state electronics seems to have led the field. 

Booser, R. E. (1988). Handbook of Lubrication, Theory and Practice of Tribology Volume II. Boca Raton CRC Press. Bowden, F. P., and Tabor, D. (1964). The Friction and Lubrication of Solids, Parr II Oxford Clarenden Press. Cameron, A. (1996). Principles of Lubrication. New York John Wiley. 

Documentation Tribology Wear, Friction and Lubrication, BAM (Federal Inst, for Testing Materials), Berlin (biennial)... 

Israelachvili, J. N., Adhesion, Friction and Lubrication of Molecularly Smooth Surfaces, Fundamentals of Friction, I. L. Singer and H. M. PoUock, Eds., Kluwer Academic Publishers, 1991,PP-351-385. 

Bowden, F. P. and Tabor, D., Friction and Lubrication of Solids, Oxford University Press, 1964. 

Gong, J. P. (2006) Friction and lubrication of hydrogels—its richness and complexity. Soft Matter, 2, 544-552. 

In spite of the strong economic importance of friction and wear and the resulting scientific effort, our understanding of the fundamental processes is still rudimentary. This results from the complexity of these topics. In addition, this complexity demands a multi-disciplinary approach to tribology. In recent years the development of new experimental methods such as the surface forces apparatus, the atomic force microscope, and the quartz microbalance made it possible to study friction and lubrication at the molecular scale. However, this new wealth of information does not alter the fact, that there are no fundamental equations to describe wear or calculate friction coefficients. Engineers still have to rely largely on their empirical knowledge and their extensive experience. 

In 1987 Mate et al. [468] used, for the first time, an atomic force microscope (AFM) to measure friction forces on the nanometer scale (review Ref. [469]). This technique became known as friction force microscopy (FFM) or lateral force microscopy (LFM). To measure friction forces with the AFM, the fast scan direction of the sample is chosen perpendicular to the direction of the cantilever. Friction between the tip and the sample causes the flexible cantilever to twist (Fig. 11.7). This torsion of the cantilever is measured by using a reflected beam of light and a position-sensitive detector in the form of a quadrant arrangement of photodiodes. This new method made it possible for the first time to study friction and lubrication on the nanometer scale. 

In 1988 a modified surface forces apparatus (SFA) was introduced [470,471] to analyze friction. The principle of operation of the SFA has already been introduced in Section 6.4. The modified version allowed a relative shearing of the two mica surfaces. In the SFA, the substrate has to have an atomically flat, transparent surface. In most cases mica is used to fulfill these requirements. Although there is a strong limitation in the choice of materials, due to the high resolution in the vertical direction, the SFA has become an important tool to study the friction and lubrication properties of molecularly thin films. 

The reduction of friction by lubricants was a prerequisite for the industrial revolution. Lubrication helps to reduce energy consumption and increase the lifetime of machines by minimizing wear. Without lubricants, almost no machine made of metal would work. It is not surprising that the phenomenon of friction and lubrication was of interest since ancient times. We know that the Egyptians wetted the sand on which they transported their stones, to reduce friction [493],... 

F.P. Bowden, D. Tabor, Friction and Lubrication, Methuen, London, 1954. 

Johnson, S.A., Gorman, D.M., Adams, M.J., and Briscoe, B J., The friction and lubrication of human stratum comeum, thin films in tribology, Dowson, D. et al. (eds.), Proceedings of the 19th Leeds-Lyon Symposium on Tribology, Elsevier Science Publishers, B.V., 1993, pp. 663-672. 

Bowden FP, Tabor D (1964) The friction and lubrication of solids—part 2. Clarendon Press, Oxford... 

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