Bearings, applicability ceramics

Calcium and Phosphate Salts Bloactive Glass Granules Bloactive Glass-Ceramic Granules Orthopedic Load-Bearing Applications... 

Ideally, before we use a ceramic in a load-bearing application we would like to have the following information about it ... 

Flaws dominate the mechanical properties of ceramics. They determine how we test them and how we design components from them. Flaws are also the reason why ceramics are stronger in compression than tension. In this chapter we described the methods used to measure mechanical properties of ceramics. The important ones are bend testing, compression testing, and indentation. To determine the mechanical properties of small volumes we use nanoindentation. This technique is especially important for thin hlms, surfaces, and nanomaterials. An understanding of statistics is particularly important when using ceramics in load-bearing applications. The Weibull approach is the one most widely used for ceramics. 

Creep is time-dependent permanent deformation that is often due to diffusion processes rather than dislocation motion. Engineers need to consider creep in cases in which ceramic components will be used in load-bearing applications at high temperature. It is necessary to specify a particular maximum strain that is acceptable during the anticipated lifetime of the component. 

You have been hired as a consultant and asked to choose the best ceramic for a load-bearing application. A vendor has offered you the following options which one would you take and why Are there any other factors that you need to consider before you make your final recommendation ... 

The three main classes of material from which we can select for a load-bearing application are metals, polymers, and ceramics. Table 35.2 is a comparative list of the significant physical properties of different biomaterials from each of the three classical material classes. Table 35.3 compares the behavior of these different classes relevant to their potential use as implants. 

The potential for extremely low clinical wear rates, necessary to reduce the risk of osteolysis, has led to renewed interest in developing new COC designs for hip arthroplasty during the 1990s (Boehler, Plenk, and Salzer 2000). In addition, the desire to reduce the fracture risk has led to continuous improvement of ceramic maferials for orthopedic load bearing applications over the past since the early 1980s (Table 6.2). 

Due to their chemical nature, ceramics and glasses (bioactive and nonbioactive) have been used in several biomedical applications, in particular for bone replacement, but their brittleness makes them unsuitable for load-bearing applications. 

Motis - A wear grade for bearing applications against hard counter-faces such as metal and ceramics. Designed for arthroplasty (joint formation) devices. 

Silica-based BGs are a group of surface-reactive glass-ceramic (GC) biomaterials, first prepared by Hench et al. in 1969 [38]. BGs possess excellent biocompatibility, the ability to bond with bone and other tissues and stimulatory effects on bone ceU function [39 1] which explain their successful application as bone-substitute material for non-load-bearing applications in orthopaedic and dental surgery [41,42],... 

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