Three-body abrasive wear

Abrasive wear occurs when asperities of a rough, hard surface or hard particles slide on a softer surface, and damage the interface by plastic deformation or fracture in the case of ductile and brittle materials, respectively. In many cases, the wear mechanism at the start is adhesive, which generates wear particles that get trapped at the interface, resulting in three-body abrasive wear. In most abrasive wear situations, scratching is observed with a series of grooves parallel to the direction of sliding.75... 

In abrasive wear by hard particles we often find either two-body abrasive wear or three-body abrasive wear, as shown in Figure 5.3. Two-body wear is caused by hard protuberances on the counterface, while in three-body wear hard particles are free to roll and slide between two sliding surfaces. Wear rates due to three-body abrasion are generally lower than those due to two-body abrasion. Various mechanisms of material removal in these two cases differ only in relative importance. Slurry erosion belongs to the abrasive wear category. Erosion is caused by hard particles sticking to the surface entrained in a flowing liquid. 

Figure 5.3 Abrasive wear by hard particles often means either two-body abrasive wear or three-body abrasive wear (a) three body and (b) two body.

The wear situation is likely to be aggravated should hard additives of a coarser grain fraction be embedded in a softer matrix, such as clay, as the result of an upstream kneading process. This may lead to grain sliding wear (besides a two-body and even a proper three-body abrasive wear), which could, in the absence of an intermediate lubricating medium, have drastic consequences. Similarly, lack of an intermediate medium will favour any likely adhesive wear. 

Whilst the wear at the deeper cut flow channels has the profile of an erosion, three-body abrasive wear may occur, just as in the solids zone, if the flow cross-sections are reduced, as shown in illustration 6. 

Fig. 6 Schematic representation of the three-body abrasive wear...

Abrasion is a form of cohesive wear that can occur in two modes, viz. two-body and three-body abrasive wear. Two-body abrasion refers to a hard rough surface, of which the asperities plough through the relatively stiffer counterface. The surface penetrations cause localised plastic displacement and indentations. Three-body abrasion refers to hard particles between two sliding surfaces, ploughing through at least one of the surfaces. The two are not mutually exclusive, as two-body abrasion can often lead to three-body when hard wear particles are detached from a surface. Abrasive wear is dependent on the bulk properties of the materials and the geometry of... 

Yousif, B. F. and El-Tayeb, N. S. M. (2008a). High-stress three-body abrasive wear of treated and untreated oil palm fiber-reinforced polyester eomposites. Proceedings of the Institution of Mechanical Engineers, PartJ Journal of Engineering Tribology 222(5), 637-646. 

MISRA A. and FINNIE I. An experimental study of three body abrasive wear" WEAR, 85 (1983) 57-69... 

Attrition is the mechanical removal of hard tissue by direct contacts between teeth (either natural or restored) with no foreign substance intervening [5]. This mechanism causes wear by tooth-tooth contacts as well as by tooth-restoration, and indeed restoration-restoration contacts. The action of mastication and bruxism are known causes of attrition. In the field of tribology, the term abrasion refers to the loss of material from a surface by sliding, rubbing or scratching. Two-body abrasion refers to abrasion caused by two contacting surfaces in relative motion, i.e. the mechanism in dentistry that is described as attrition. Three-body abrasion refers to abrasion caused by surfaces in... 

The lapping process is a very complex three-body abrasion. During friction and wear processes, many AE signals could be generated because of the interactions, impact, dislocation, deformation, and removal of materials. In the area of tribology, AE was used to characterize wear mechanisms, discern plastic deformation and fracture, and to monitor active friction and wear processes. AE signals were related to friction coefficient, abrasive grit size, and wear rate. 

Buijs, M., and Korpel-van Houten, K., Three-body abrasion of Brittle materials as studied by lapping. Wear, Vol. 166,1993, pp. 237-245. 

Particle cleavage (erosion) Freely moving particles, which are carried in an intermediate medium between the base and counter body cause the wear (three-body abrasion). 

Probably, the change in wear coefficient with slurry concentration can be explained by the ease of particle entrainment into the contact area and as a result of that, by the transition in wear mechanism from three- to two-body wear. Trezona et al showed that a minimum concentration of abrasive particles is needed to ensure three-body rolling wear [6]. The abrasive particle concentration in the contact area will decrease with increasing load and with decreasing slurry concentration. This means that on the left-hand side in figure 5, with a normal load of 0.5 N, wear will be predominantly two-body grooving. 

Abrasive wear is defined as the material loss when a hard particle is made to slide against a soft material. Abrasive wear is classified as two-body abrasion or three-body abrasion. In two-body abrasion, abrasive particles move freely over a material face as in sand sliding down a chute. In three-body abrasion, abrasive particles act as interfacial elements between the solid body and the counter body. It can be classified as high stress abrasion or low stress abrasion depending on the applied stresses. 

The work of Soemantri et al. [76] is presented in Fig. 6.15. Figure 6.15a shows the results of the two-body abrasion test, whereas Fig. 6.15b pertains to three-body abrasion. This work was carried out with commercially pure Al and Cu. As can be seen from Fig. 6.15, the wear rate of Cu is independent of temperature for two-body abrasion. Similarly, the two-body abrasive wear rate of Al is also nearly constant even though an increase in wear rate is noted at 323 K. In contrast, the wear rate of Cu increases with increase of temperature during three-body abrasion. However, for Al, the three-body... 

Effect of test temperature on abrasive wear rate (a) two-body abrasion (b) three-body abrasion [76]. 

For testing dental restorative materials, many regimes exist that use similar principles to those described for assessing toothpaste abrasivity. These tests may be conducted under conditions of two-body or three-body wear [25], i.e. focussing either on attrition or abrasion. Two-body tests for restorative materials either use human enamel [26] or a hard material, such as alumina [27] or steatite [28], as the abrader. For three-body tests, an abrasive medium, such as toothpaste slurry [29, 30], or an abrasive food, such as rice or millet seeds [31,32], is typically used. These test methods are usually not truly representative of the oral environment rather, they are designed to assess the wear resistance of restorative materials under extreme conditions. 

Abrasive Wear Categories. Abrasion is typically categorized according to types of contact, as well as contact environment. Types of contact include two-body and three-body wear. The former occurs when an abrasive slides along a surface, and the latter, when an abrasive is caught between one surface and another. Two-body systems typically experience from 10 to 1000 times as much loss as three-body systems for a given load and path length of wear. Contact environments (Fig. 5) are classified as either open (free) or closed (constrained). 

Fig. 5 Types of contact during abrasive wear, (a) Open two-body, (b) Closed two-body. (c) Open three-body, (d) Closed three-body...

When a conqxinent has surfaces that roll or slide against others with abrasive and/or corrosive product trapped between them, it creates the very extreme condition of three-body high-stress abrasive wear (see... 

Surface treatments for three-body high-stress abrasive wear and corrosion applications are limited to those which provide a combination of hardness, toughness, load-carrying capacity, and corrosion resistance. 

Keywords Abrasive wear, grooving wear, rolling wear, two-body wear, three-body wear. Microscale abrasion, Polyoxymethylene, Polyamide 6.6, Polybuthylene terephthalate, Polytetrafluoroethylene. 

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