Preparation and characterization of sol-gel hydroxyapatite and its electrochemical evaluation for biomedical applications.

Metallic materials having good mechanical properties, high corrosion resistance, and good compatibility with biological materials are used as orthopedic devices. Type 316L stainless steel is the most widely used material for implant fabrication in India for orthopedic applications owing to their good corrosion resistance, hot and cold workability, excellent mechanical properties, and availability at low cost. However, it faces corrosion-related problems in physiological environment and thus releases toxic metal ions into the tissues surrounding the implants. Hence, hydroxyapatite (HAP) coatings over the metal implant have been developed as an alternative method to improve the surface conditions of the base metal. In the present investigation, the development of a sol-gel-derived hydroxyapatite coating on 316L SS is being explored. The corrosion resistance behavior of the coating was assessed through electrochemical studies involving cyclic polarization experiments and impedance analysis in Ringer's solution. The results have indicated that the sol-gel-derived HAP coatings exhibited excellent resistance to localized attack on pristine 316L SS. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008.