ISSN:
0021-9304
Keywords:
NiTi shape memory alloy
;
stents
;
surface treatments
;
corrosion resistance
;
surface characterization
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
,
Technology
Notes:
Because of its good radiopacity, superelasticity, and shape memory properties, nickel-titanium (NiTi) is a potential material for fabrication of stents because these properties can facilitate their implantation and precise positioning. However, in vitro studies of NiTi alloys report the dependence of alloy biocompatibility and corrosion behavior on surface conditions. Surface oxidation seems to be very promising for improving the corrosion resistance and biocompatibility of NiTi. In this work, we studied the effect on corrosion resistance and surface characteristics of electropolishing, heat treatment, and nitric acid passivation of NiTi stents. Characterization techniques such as potentiodynamic polarization tests, scanning electron microscopy, Auger electron spectroscopy, and X-ray photoelectron spectroscopy were used to relate corrosion behavior to surface characteristics and surface treatments. Results show that all of these surface treatments improve the corrosion resistance of the alloy. This improvement is attributed to the plastically deformed native oxide layer removal and replacement by a newly grown, more uniform one. The uniformity of the oxide layer, rather than its thickness and composition, seems to be the predominant factor to explain the corrosion resistance improvement. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 43: 433-440, 1998
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
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