TABLE OF CONTENTS As mentioned at the beginning of this chapter, most of the traditional methods of controlling corrosion cannot be used for surgical implants as the environment within the human body is fixed. The only methods available are to fabricate the implants from a corrosion-resistant alloy or to use a coating either of which must be able to withstand any abrasion and wear to which the device may be subjected. Nevertheless, a number of steps must be taken to help reduce the risk of corrosion related failures of surgical implants [100,101].
Paints and other forms of organic coating have a very limited (if any) role in protecting implants, since they are unable to withstand abrasion. Coatings that may be of use include titanium or titanium nitride films on Ni-Ti memory-shape alloys [102] and very high chromium ferritic stainless steel claddings on rare earth magnets used as dental keepers. The poor fretting resistance of the Ti-6Al-4V alloy represents its most serious drawback with regards to its use as an implant material; thus considerable effort has been dedicated to improving its surface properties. Techniques that have yielded the most encouraging results are anodizing [16] and generating of titanium nitride coatings either by ion implantation [62], magnetron sputtering [103], or nitriding [63,64].
Many corrosion related failures of surgical implants can be traced back to poor quality control. Problems usually stem from one of two points in the supply line. Firstly the manufacturer must follow the...
