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Corrosion resistance, chemistry, and mechanical aspects of Nitinol surfaces formed in hydrogen peroxide solutions
Author(s) -
Shabalovskaya Svetlana A.,
Anderegg James W.,
Undisz Andreas,
Rettenmayr Markus,
Rondelli Gianni C.
Publication year - 2012
Publication title -
journal of biomedical materials research part b: applied biomaterials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 108
eISSN - 1552-4981
pISSN - 1552-4973
DOI - 10.1002/jbm.b.32717
Subject(s) - x ray photoelectron spectroscopy , materials science , corrosion , auger electron spectroscopy , oxidizing agent , oxide , aqueous solution , metallurgy , chemical engineering , chemistry , physics , organic chemistry , nuclear physics , engineering
Ti oxides formed naturally on Nitinol surfaces are only a few nanometers thick. To increase their thickness, heat treatments are explored. The resulting surfaces exhibit poor resistance to pitting corrosion. As an alternative approach to accelerate surface oxidation and grow thicker oxides, the exposure of Nitinol to strong oxidizing H 2 O 2 aqueous solutions (3 and 30%) for various periods of time was used. Using X‐Ray Photoelectron Spectroscopy (XPS) and Auger spectroscopy, it was found that the surface layers with variable Ti (6–15 at %) and Ni (5–13 at %) contents and the thickness up to 100 nm without Ni‐enriched interfaces could be formed. The response of the surface oxides to stress in superelastic regime of deformations depended on oxide thickness. In the corrosion studies performed in both strained and strain‐free states using potentiodynamic and potentiostatic polarizations, the surfaces treated in H 2 O 2 showed no pitting in corrosive solution that was assigned to higher chemical homogeneity of the surfaces free of secondary phases and inclusions that assist better biocompatibility of Nitinol medical devices. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 100B: 1490–1499, 2012