Micromechanics of machining and wear in hard and brittle materials

Abstract

Shaping in production and ensuing wear resistance during service loom as critical factors in the manufacture of hard and brittle components for high technology applications. By "hard and brittle" we mean solids with predominantly covalent and ionic bonding-advanced ceramics, glasses, semiconductors, and many biomaterials. Underlying the machining and wear behavior of this class of solids is the competitive interplay between plastic (or quasiplastic) deformation and brittle fracture in concentrated loading. Mechanical machining/wear is essentially a contact problem, more accurately a microcontact or nanocontact problem, fundamentally established in terms of indentation mechanics. 1-9 A principal factor in achieving acceptable surface finish is the scale of individual contacts. It has long been known to those involved in glass finishing with abrasive slurries that coarse particles produce

Nanoindentation pop‐in in oxides at room temperature: Dislocation activation or crack formation?

“…for bi‐crystals of high quality. Third, dislocations can be introduced into samples by mechanical deformation, for example, via bulk compression at room temperature 28‐32 or high temperature, 13,15,33 by near surface mechanical treatment using nanoindentation at a small scale, 34‐40 micro‐scratching/machining, 41 and so on. While the first two approaches mainly involve processing and fabrication, the third approach relies on the dislocation mechanics of the target ceramic materials under mechanical loading.…”

The influence of carbon on the microstructure and wear resistance of alumina

“…Inspection of Figure 7C reveals a good linear fit according to the model of Davidge and Riley for the carbon‐doped black alumina, indicating that the mechanism of wear involves the formation and propagation of microcracks at grain boundaries 5 . Because cutting is typically an abrasive wear process 45 and the features observed here, namely intergranular fracture, wear flats, and tribofilms, are consistent with abrasive wear, 55 it is expected that the model of Davidge and Riley should describe the dependence of cutting rate on grain size. The white and gray samples fit the model only for the smaller grain sizes and show an almost identical behavior in this region (shaded in yellow in Figure 7C).…”

“…To the best knowledge of the authors, a model for cutting rate does not exist for polycrystalline ceramics. The model for wear was adapted here since cutting under certain conditions may be described as an abrasive wear process 45 . As discussed below, microstructure observations on cut surfaces reveal features consistent with abrasive wear.…”

“…The model for wear was adapted here since cutting under certain conditions may be described as an abrasive wear process. 45 As discussed below, microstructure observations on cut surfaces reveal features consistent with abrasive wear. According to the model proposed by Davidge and Riley, a linear intercept with the origin demonstrates a correlation of the wear rate with the grain size, where G 0 ranges between 1 µm and 100 µm.…”

Optimisation of Lapping Process Parameters for Single-Crystal 4H–SiC Using Orthogonal Experiments and Grey Relational Analysis

“…Grinding/lapping is a critical planarization process approach to obtain a high-quality single-crystal 4H–SiC substrate surface, mainly using high-hardness wheels/abrasives to efficiently remove cut marks and rough peaks on the sliced SiC substrate’s surface to reduce surface roughness and improve surface flatness for polishing [ 6 ]. However, during the grinding process, the grinding wheel and the substrate have a two-body friction movement that can lead to a strong TTV [ 7 , 8 ], though with relatively greater subsurface damage. In order to reduce the polishing time while improving the TTV and minimizing sub-surface damage, lapping (which mainly comprises three-body friction movement and less two-body friction movement) can be used.…”