Tribology defined

The calculation of electrostatic interactions in FF-based tribological simulations also requires care. The typical model used in tribological simulations consists of two surfaces separated by a fluid, with the whole system subject to periodic boundary conditions (PBCs). If we define the system such that the surfaces extend in the x — y plane, it seems only natural to apply PBCs in these two dimensions. Flowever, care must be taken when treating the third dimension z, which lies normal to the surfaces. Specifically, one must ensure that the length of the simulation cell in the z direction is large enough to leave... 

The second approach used in first-principles tribological simulations focuses on the behavior of the sheared fluid. That is, the walls are not considered and the system is treated as bulk fluid, as discussed. These simulations are typically performed using ab initio molecular dynamics (AIMD) with DFT and plane-wave basis sets. A general tribological AIMD simulation would be run as follows. A system representing the fluid would be placed in a simulation cell repeated periodically in all three directions. Shear or load is applied to the system using schemes such as that of Parrinello and Rahman, which was discussed above. In this approach, one defines a (potentially time-dependent) reference stress tensor aref and alters the nuclear and cell dynamics, such that the internal stress tensor crsys is equal to aref. When crsys = aref, the internal and external forces on the cell vectors balance, and the system is subject to the desired shear or load. 

Erosion is defined as the loss of hard tissue by chemical means not derived from bacteria, i.e. the dissolution of hard tissue by acid where the acid source is not the oral bacteria [5], Erosion may be caused by either intrinsic (e.g. stomach acid) or extrinsic (e.g. dietary) sources. Erosion is often associated with the consumption of acid products, such as fruits or acid beverages, or with medical conditions where reflux of acidic into the oral cavity is present. Interestingly, the term erosion is widely used in other fields where the definition is rather different. For example, in the field of tribology, erosion refers to the loss of material from a surface by solid or liquid impacts [6], In the classical tribological definitions, the mechanism dentists refer to as erosion would be described as corrosion, or tribo-chemical wear. 

The word tribology, derived from the Greek to rub, covers aU frictional processes between solid bodies moving relative to one another that are in contact [2]. Thus tribology may be defined as the study of... 

Readers are cautioned against the use of various terms in tribology which are either vaguely defined or not defined at all. These would include such terms as lubricating ability, lubricity, and even boundary lubrication. For example, do boundary lubricating properties refer to effects on friction or effects on wear and damage It makes a difference. It is emphasized once again that friction and wear are different phenomena. Low friction does not necessarily mean low wear. We will see several examples of this common error in the discussion of joint lubrication research. 

The elements of such a system consist of the primary body, the counter body, the interfacial medium and surrounding medium. Wear is a result of the action of the collective stress on the structure respectively on the elements of the tribological system and manifests itself in energetic and material interactions between these elements. It is defined by the wear parameters. Basically all wear mechanisms can occur abrasion, adhesion, tribo-chemical reactions or wear caused by fatigue. In the case of the extrusion of ceramic bodies, corrosion must be considered as another harmful mechanism. When determining the elements of the tribosystem for the... 

Equation 6 applies to the analysis of fluid behavior in tribology and microchannel flows this kind of flow is called Stokes flow. In this case, the velocities are free of macroscopic fluctuations at any point in the flow field and the flow is defined as laminar. 

Mechanochemistry (or Tribochemistry) is usually defined as a science dealing with the chemical and physicochemical changes of substances due to the influence of mechanical energy [23] (see Appendix A for other definitions of mechanochemistry). On the other hand, the term tribology is commonly used to refer to the science of interacting surfaces in relative motion with respect to friction, lubrication, and wear [41]. 

Rohr, F E. (2003) Paint Coat. Ind., Defining and Predicting Performance of Surface Modifiers in Coatings, 19 (10), 110, accessed atwww.pcimag.com. SpecialChem. SA. (2003) Additives for tribological polymers used in bearing applications, article accessed at www. specialchem4polymers.com/resources/ articles. 

Corrosion science and engineering is a complex and broad subject that is not well defined and is still evolving as the subject itself expands beyond the traditional one, the destructive oxidation of metals, to the subject of this report, environmentally induced degradation of a material that involves a chemical reaction. The newer subject matter encompasses a wide spectrum of environments and all classes of materials, not just metals, and it intentionally excludes degradation due to nonchemical processes such as creep, fatigue, and tribology. 

The morphology of the wear tracks and the ball used for the tribotest were examined with an optical microscope. The ball shows a circular fiat spot with a diameter of 150/ tm, which was worn off mainly during the running-in period of the tribotest. It defines the apparent contact area during subsequent tests. On the tribologically stressed disk, the areas tested with 5 and 1 N are clearly visible by optical microscopy, but for lower loads no differences can be recognized between the contact and the non-contact area. Without additional information from imaging XPS it would be difficult to locate the areas tested at lower loads. 

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