The clinical demands on new load bearing orthopedic and spinal implants, could benefit from recent development in process engineering of metals, such as equal channel angular extrusion, for the fabrication of nano-grain raw materials. These demands include strength and fatigue performance. In concert with the mechanical properties of implant materials, biocompatibility and biostability are critical for long-term efficacy of metals utilized in therapeutic or chronic implantable medical devices. These attributes are primarily dictated and influenced by the properties of the surface oxide film, typically 2 to 10 nm in thickness. These oxides are the critical interfacial feature that governs the interaction between the metallic biomaterial and the biological environment.

Electrochemical techniques were utilized to study the polarization behaviors of oxide films on nano-grain and commercial titanium alloys as they permit the rapid evaluation of the corrosion resistance of a metal in a test electrolyte by accelerating one or more naturally occurring reactions. Several quantitative parameters can be extracted from the electrochemical experiments, such as corrosion rates, pitting resistance, passivation tendencies etc.

This paper discusses the effects of grain size, anodization treatment, surface chemistry, and electron donor density on the corrosion resistance of novel and commercially available CpTi and Ti-6Al-4V alloys targeted for orthopedic and spinal application.