And lubricated wear

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... 

Kulczycki, A. (1985) The correlation between results of different model friction tests in terms of an energy analysis of friction and lubrication. Wear 103 67-75. 

The effect of such operating parameters as load and rubbing speed on the quantitative relation of dry and lubricated wear is neither simple nor obvious. Table 13-4 shows two direct comparisons one of data from the work of Kerridge and Lancaster [15] and the other of unpublished data... 

The preceding chapter was devoted to the development of the fundamental concepts of mechanical wear and to the examination of generalized wear phenomenology in relation to these concepts. The same basic mechanistic processes govern both unlubricated and lubricated wear. The role of the lubricant in lubricated wear is essentially to ameliorate wear by modifying the extent and the rates of those basic processes that exert the critical influences in whatever particular case is under examination. Unlubricated wear is not necessarily simpler or more elementary than lubricated wear in fact, unlubricated wear is more likely to be so destructive under severe conditions that it may be effectively impossible to specify what occurred at a given stage of the wear process. 

In the discussions of Chapter 13 there was no categorical separation of unlubricated and lubricated wear. Given the existence of an unbroken film of liquid lubricant between two surfaces, it is generally expected that no wear will occur. This is not always so transmission of hydrostatic pressure through the film can plastically deform the bodies which it separates, and tangential tractive forces in the film can do the same. These are wear phenomena as defined in Chapter 13, and since they occur in the presence of lubricant they can be formally classified as lubricated wear. However, in this chapter we shall not concern ourselves with these particular aspects of lubricated wear. We shall be concerned instead with the course of wear in situations where the behavior of the lubricant does not. conform fully with the laws of hydrodynamics or elas-tohydrodynamics. The inference, of course, is that the lubricant at the rubbing surfaces is not there as an unbroken film. 

These things are well known and numerous specific papers and review articles emphasise these points from various viewpoints (1-9). In summary, the tribology of PTFE, althoi gh somewhat unusual in some respects, is not exceptionally different from that of other organic polymers, particularly low temperature (gross softening below ca. 350°C) thermoplastics. The review will focus on the way in which PTFE differs from other polymers bearing in mind that these differences are not really ones of kind but of extent. Three topics will be discussed abrasive wear, transfer wear and lubricated wear. 

The temperature rise associated with both the dry and lubricated wear tests did not exceed 90°C. Such a temperature rise can be associated with the low coefficients of friction (and carrier mechanisms during the lubricated tests). Such increases are not sufficient to noticeably alter the properties of the CVD diamond or to breakdown the mineral oil lubricant. 

VERGNE Ph., BERTHE D. and FLAMANO L. "Glassy transition of various lubricants", in Mixed Lubrication and Lubricated Wear, Leeds, September 1984. 

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