Surface Characterization and Corrosion Resistance of Generation I-III Nitinol with Various Surface Finishes

Although improvements in fatigue performance with increasing Nitinol microstructural purity have been previously characterized, there is limited information on whether corrosion resistance is impacted by reductions in inclusion size and distribution. The objective of this study is to characterize the surface oxide for different Nitinol microstructural purities and determine its influence on corrosion susceptibility. To assess the surface oxide, X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS) were performed on Nitinol heart valve frames with a variety of purities and surface finishes.