Characterization of ‘As-Received’ Nickel – Titanium Alloy Wire by Cyclic Potentiodynamic Polarization

It is well understood that the surface finish of nickel-titanium alloy wire control its resistance to corrosion during cyclic potentiodynamic polarization (CPP). In phosphate buffered saline solutions, differences in breakdown potentials differ by over 800 mV , . Nickel-titanium wire is commercially available in a variety of surface finishes ranging from “Black' to ‘Bright.' This study was carried out to determine what affect commercially available surface finishes have on the corrosion resistance of the ‘, as-received' wire. Wire with varying levels of oxide coatings (‘Black Oxide,' ‘Dark Oxide,' and ‘Light Oxide') as well as “Bright” finishes available for a same source, were chosen for investigation following the protocol described in ASTM F2129 . Differences in the corrosion appearance and performance of the wire with respect to the rest potential (Er), breakdown potential (Eb) and protection potential (Ep) are reported.