Tribology, objectives

One of the primary goals of current research in the area of tribology is to understand how it is that the kinetic energy of a sliding object is converted into internal energy. These dissipation mechanisms detennine the rate of energy flow from macroscopic motion into the microscopic modes of the system. Numerous mechanisms can be... 

Virtually in all dry sliding contacts we observe that the frictional force required to initiate motion is more than that needed to maintain the surfaces in the subsequent relative sliding thus there are two values reported for the coefficient of friction. The static coefficient of friction is used in reference to the initial movement of the object from the rest position. In this case, the F ml. The kinetic coefficient of friction is used for two surfaces in relative motion. This feature, together with the inevitable natural elasticity of any mechanical system, can often lead to the troublesome phenomenon of stick-slip motion (the displacement of surface materials with time). Displacement increases linearly with time during periods of sticking when slipping occurs, the deformed surface materials are released. Representative of dry static and kinetic coefficients of friction for various material pairs are found in tribology and physics references 11 see Table 3.1. 

Measuring the tribological properties of diamond films turns out to be rather complicated for several reasons. For running such an experiment between two diamond objects, the tip or ball of the tribometer has to be coated with diamond too, which constitutes a technological challenge. Using softer tips instead may in some cases lead to a material transfer from the tip to the diamond surface under test, resulting in a modified surface with altered mechanical properties. The surface coarseness is also complicated to measure and hard to adjust Finally, problems in the diamond film s adhesion to the substrate constitute another parameter to be controlled. 

Historical review of tribological studies of metallic and ceramic bearing surfaces used for total hip arthroplasty (THA). Presents an objective assessment of wear mechanisms, wear measurement, laboratory studies, and clinical observations for THA. 

Friction and wear properties Both friction and wear belong to the discipline of tribology. Friction is the force of two surfaces in contact or the force of a medium acting on a moving object, and wear is the erosion of material from a solid surface by the action of another solid. Factors that exert influence on friction and wear characteristics of polymer composites are the particle size, morphology, and concentration of the filler [38]. 

The objective in this paper is to clarify the film thickness effect of Ag films in the range from 0.4 nm to approximately 170 nm under limited conditions due to the asperities in the contact area and the atmospheres. The relationship between the tribological properties and nano structure of Ag is the special focus of this study. 

A workshop was held in 2002 to discuss the structure and initial content of a possible future expert system for XPS [132]. These discussions led to many recommendations concerning instrument and specimen characterization, experimental objectives, instrument setup, acquisition and analysis of survey scans, protocols for narrow scans and analysis of results, identification of chemical state and sample morphology, and quantitative analyses. These recommendations are believed to be a valuable source of best practices as well as an educational resource for both novice and experienced users. Castle has recently designed a module for an XPS expert system that would guide corrosion scientists [133] and has shown design goals for similar applications in catalysis, adhesion science, tribology, and biomaterials [134]. 

The objective is to deposit a ceramic layer on a support (metal, ceramic, organic) to obtain surface properties different from the massive material. The applications of these coated materials are numerous (tribology, heat insulation, corrosion resistance, electronics, optics, optoelectronic, biomedical, etc.). The thickness of the layers can vary from a few atomic layers for techniques of vacuum deposition (they are called thin layers) to a few milUmeters in the case of plasma spraying. 

Tribology may be defined as the friction, lubrication and wear of engineering surfaces in relative motion. The objective is to imderstand in basic terms the mechanisms involved when two surfaces interact during sliding, and to subsequently apply this knowledge to the optimization of industrial processes. In the case of elastomeric or rubberlike materials, we assume that they slide on a rough, rigid base surface with or without interfacial lubrication. 

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