Lubrication behavior

Tribological Behavior. Tribological performance of ceramics, which includes friction, adhesion, wear, and lubricated behavior of two soHd materials in contact, has been reviewed (52). 

Interface slip factor a (m ). This factor is defined as a phenomenological parameter characterizing the lubrication behavior on the phase interface as a slide occurs. 

However, investigations up to now have mainly concentrated themselves on ambient environments even though it is known that ionic liquids have a very low vapor pressure, making them suitable for vacuum applications such as in space mechanisms, the disk drive industry, and microelec-tromechanical systems (MEMS). Due to the ultra-low vapor pressure of most ionic liquids, they have been expected to be good lubricants in vacuum. Further experimental works are required to evaluate lubrication behavior of ionic liquids under ultra-high vacuum conditions and in inert atmospheres. 

In literature, some researchers regarded that the continuum mechanic ceases to be valid to describe the lubrication behavior when clearance decreases down to such a limit. Reasons cited for the inadequacy of continuum methods applied to the lubrication confined between two solid walls in relative motion are that the problem is so complex that any theoretical approach is doomed to failure, and that the film is so thin, being inherently of molecular scale, that modeling the material as a continuum ceases to be valid. Due to the molecular orientation, the lubricant has an underlying microstructure. They turned to molecular dynamic simulation for help, from which macroscopic flow equations are drawn. This is also validated through molecular dynamic simulation by Hu et al. [6,7] and Mark et al. [8]. To date, experimental research had "got a little too far forward on its skis however, theoretical approaches have not had such rosy prospects as the experimental ones have. Theoretical modeling of the lubrication features associated with TFL is then urgently necessary. 

One important point for understanding the lubrication behavior of zinc dialkyldithio-phosphates consists of their participation in electron-transfer reactions. As shown, anion radicals of these salts are cleaved according to this scheme (Kajdas et al. 1986) ... 

Muller BW. Polymorphism of magnesium stearate and the influence of the crystal structure on the lubricating behavior of excipients. Acta Pharm Suec 1981 18 7A—75. 

Chemical heterogeneity of a surface is an important property affecting adhesion, adsorption, wettability, biocompatibility, printability and lubrication behavior of a surface. It seriously affects gas and liquid adsorption capacity of a substrate and also the extent of a catalysis reaction. As an example, the partial oxidation of carbon black surfaces has an important, influence on their adsorptive behavior. In a chemically heterogeneous catalyst, the composition and the chemical (valence) state of the surface atoms or molecules are very important, and such a catalyst may only have the power to catalyze a specific chemical reaction if the heterogeneity of its surface structure can be controlled and reproduced during the synthesis. Thus in many instances, it is necessary to determine the chemical... 

As stated in Chapter 1, the chemical structure of the top surface layers of a solid determines its surface properties. If these top layers consist of the same chemical groups, then the surface is called chemically homogeneous, and if they consist of different chemical groups it is called chemically heterogeneous. The presence of two or more chemically different solid substances in a surface layer enormously multiplies the possibilities for variety in the types of surface, such as copolymer surfaces and catalysts having many different atoms at the surface. The chemical heterogeneity of a surface is an important property in industry affecting catalysis, adhesion, adsorption, wettability, biocompatibility, printability and lubrication behavior of a surface, and it must be determined analytically when required. 

In this book we shall begin with an examination of hydrodynamic lubrication. If there is a mode of real lubrication behavior which approaches the ideal, it is simple hydrodynamic lubrication. There is no contact of the solid surfaces and therefore no wear in the generally accepted sense the friction is that arising from the viscous shear of the lubricating fluid. The part that the viscosity and the density of the lubricating fluid plays in hydrodynamic lubrication leads us from engineering physics to the physical chemistry of liquids. 

In this section we shall start with an examination of lubrication behavior under conditions in which the existence of an adsorbed film and the nature of its properties are known positively. The information so obtained will then be applied to discussions of experiments carried out under less rigorous control. 

When a chemically deposited film of "friction polymer" or "surface resin" derived from precursors intrinsically part of a petroleum oil acts as an additive in the high-pressure lubricant behavior of that oil, then the function of the oil must be viewed in a two-fold light. That part of the oil which generates the surface film is in effect an additive. The rest of the oil is the inert liquid carrier. 

Table 17-6 indicates that concern with the intrinsic influence of the specific lubricant on wear is valid. The fluids listed there are of low viscosity because they were investigated for low-temperature hydraulic service [14], However, the extent of wear shows no direct relation to viscosity the silicate fluid, which permits the most wear, is not the least viscous of the fluids tested, and the silicone, which is the most viscous, is not the one which gives the best antiwear rating. Figure 17-4 shows intrinsic lubricant behavior in a different version of... 

Tribology is the study of adhesion, friction, wear and lubricated behavior of materials in solid state contact. It was in the early 1980s that the advantage of... 

The lubricating behavior of M0S2 is not affected by exposure to nuclear radiation. 

---