Artificial joint protection

Although titanium has a large positive E° for oxidation, and T dust will burn in air, the bulk metal is remarkably immune to corrosion because its surface becomes coated with a thin, protective oxide film. Titanium objects are inert to seawater, nitric acid, hot aqueous NaOH, and even to aqueous chlorine gas. Titanium is therefore used in chemical plants, in desalination equipment, and in numerous other industrial processes that demand inert, noncorrosive materials. Because it is nontoxic and inert to body fluids, titanium is even used for manufacturing artificial joints and dental implants. 

Teflon is used as thermal insulation in clothing, as a component in wall coverings, and as a protective coating on metals, glass, and plastics. Teflon s properties of very low chemical reactivity and very low friction make it valuable in the construction of artificial joints for human limbs. As you can see in Figure 9, Teflon is also used as a roofing material. 

Scientists have used water to create almost frictionless lubricated surfaces that stay slippery even under heavy loads. The coating they have developed could shed light on how natural joints are lubricated and provide new ways to protect hip and knee joint implants from friction damage. Over time, the body s immune systan attacks artificial joints. Researchers are now targeting biological interactions rather than trying to solve the problem with new materials. 

In many polsrmers, radicals can have very long lifetimes, particularly if they are located in crystalline regions where they are protected from any added stabilizer. Jahan and co-workers (153), for example, have reported that long-lived radicals formed dining sterilization of PE artificial joint components are at least partially responsible for their long-term deterioration. In addition, Yoimg and... 

To protect the aluminum joint from the effects of the environment, especially water and corrosion, an artificially thickened oxide layer is generally formed on the surface. Historically, chemical etching as a surface preparation has provided the surest way of obtaining durable adhesive bonds with aluminum. 

---