Erosive wear mechanisms

The erosive wear mechanism, as in the case of abrasion, involves both plastic deformation and brittle fracture. The particle velocity and impact angle combined... 

The main mechanisms of hearth bottom wear are high heat load, chemical attack, erosion from molten Hquids, mechanical and thermal stress, and penetration because of ferrostatic and process pressure. A variety of special purpose carbons have been developed to minimize or eliminate the damage caused by these wear mechanisms. 

Localized deterioration Corrosion (especially pitting and intergranular attack), erosion, cavitation, mechanical wear, and so on (see Case History 9.8). 

The CMP process is regarded as a combination of chemical effect, mechanical effect, and hydrodynamic effect [110-116]. Based on contact mechanics, hydrodynamics theories and abrasive wear mechanisms, a great deal of models on material removal mechanisms in CMP have been proposed [110,111,117-121]. Although there is still a lack of a model that is able to describe the entire available CMP process, during which erosion and abrasive wear are agreed to be two basic effects. 

Walker and Bodkin (1993) discuss the advantages and limitations of a number of the commonly used erosive wear testers. The influence of particle size and shape are very important as well as the impingement angle and concentration of the slurry. They found that the wear rate increases with the jet velocity to the power of 2.2 (Mens and de Gee (1986) gives 2.8-3.2.). Wear rate is at a maximum at 30° impingement angle. The mechanism is mainly cutting. The rate increases with the size of the particle. 

The term tooth wear is commonly used to describe the loss of tooth hard tissue due to non-carious causes [1], This encompasses a variety of both chemical and mechanical causes of both intrinsic and extrinsic origin. The term tooth wear is preferred over some of the more precise definitions of individual hard tissue loss mechanisms, because it acknowledges the fact that wear is usually a multifactorial process one mechanism may dominate, but the overall wear is commonly due to the interaction between two or more wear mechanisms. In dentistry, the terms erosion, abrasion, attrition and abfraction are widely used to describe particular mechanisms of hard tissue loss. 

The mechanisms of tooth wear fall into two distinct types those of chemical origin (e.g. erosion) and those of physical origin (e.g. abrasion, attrition). In any individual, both chemical and physical insults to the tooth hard tissue will be present in some form or other, so tooth wear is the combined effect of these insults. Despite the clear definition of a number of distinct tooth wear mechanisms, it is uncommon to find a single wear mechanism present in the... 

Of particular note is the importance of erosion in accelerating tooth wear. The softening of enamel and dentine surfaces by erosive attacks from acid renders the surface extremely susceptible to mechanical attacks [9]. Abfraction is also an example of interaction between wear mechanisms, where abrasion and erosion may act in combination with cyclic loading and unloading to produce an overall wear effect. 

An alternative approach is to assess a service application in terms of the relative importance of basic wear mechanisms (abrasion, fatigue, adhesion, impact/slide, erosion etc) and the geometry and motion. Small scale tests are then carried out in the laboratory to simulate these mechanisms and parameters in order to produce relevant wear data. The performance data for each material with reference to each of these tests will therefore grade the suitability of that material to the proposed application. 

The principal wear mechanisms are (i) adhesive (ii) abrasive (iii) fatigue (iv) impact by erosion and percussion (v) chemical and (vi) electrical arc-induced. 

The effect of ultra-high molecular weight poly-(ethylene) (UHMWPE) the on mechanical and solid particle erosive wear behavior of aramid fabric reinforced-epoxy composites has been investigated [64]. A siUca sand of a size of 150-280 fim was used as an erodent. The erosive wear rate of UHMWPE in aramid-epoxy composite exhibits a lower value in comparison to neat composites. A maximum erosion rate was observed at an impingement angle 60 , and the material behaves in a semiductile manner. 

Specimens were weighed in a digital balance up to 5 decimal place before and after each erosion tests. Worn surfaces and wear debris were examined using a Hitachi S-4700 scanning electron microscope to determine possible wear mechanism operating under different test conditions. 

Higuera, V., Belzunce, F. J. Ferna ndez Rico, E. (1997). Erosion Wear and Mechanical Properties of Plasma-Sprayed Nickel- and Iron-Based Coatings Subjected to Service Conditions in Boilers. Tribological International, VoL 30, No. 9, p>p. 641-649, ISSN 0301679X... 

By the nature of the feeding mechanism, rotary valves are more suited to relatively nonabrasive materials. This is particularly the case where they are used to feed materials into positive pressure conveying systems. By virtue of the pressure difference across the valve, and the need to maintain a rotor tip clearance, air will leak across the valve. Wear, therefore, will not only occur by conventional abrasive mechanisms, but by erosive wear also. Air leakage through the blade tip clearances can generate high velocity flows, which will entrain fine particles, and the resulting erosive wear can be far more serious than the abrasive wear. Wear resistant materials can be used in the construction of rotary valves, and removable... 

The mechanisms by which wear of rubber occurs when it is in moving contact with another material are complex but the principle factors involved are cutting and fatigue. It is possible to categorise wear mechanisms in various ways and commonly distinction is made between abrasive wear, fatigue wear and adhesive wear. Additionally, wear by roll formation is sometimes considered as a separate mechanism. There can also be corrosive wear due to direct chemical attack on the surface and the term erosive wear is sometimes used for the action of particles in a liquid stream. 

Wear is the erosion of material from a solid surface induced by the action of repeated mbbing. Many wear mechanisms have been proposed such as abrasion, adhesion, surface fatigue, corrosion, erosion, and delamination. Friedrich and Sdilarb [27]... 

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