Studies of surface modified NiTi alloy


Studies of surface modified NiTi alloy

Shevchenko, N.; Pham, M. T.; Maitz, M. F.

The superelastic titanium-nickel alloy NiTi is already in use in medical applications as vascular stents and for osteosynthetic devices mainly in craniosurgery. However there are still concerns because of the high nickel content and a possible release of nickel ions, where toxicity, carcinogenicity and allergic hazards are well documented.
Bone forming cells were grown on NiTi from two suppliers, titanium, pure nickel and stainless steel. The cell adherence and the organisation of the actin cytoskeleton was severely disturbed both on the NiTi of one supplier and on pure nickel, compared with the reference material. These changes did not exist on the other NiTi preparation, the effect also could not be reproduced by nickel ions in solution. This indicates that by different preparation of the material and different surface treatment of the material its biocompatibility can be improved.
Ion implantation of Ar+ and N+ ions in NiTi with energy of 20-40 keV and fluences of (3-5)x10 17 cm-2 by means of plasma immersion ion implantation with the intention to perform preferential sputtering of Ni and to seal the surface with a TiN layer. The near surface layer was analysed by grazing incidence X-ray diffraction analysis (GIXRD), Auger electron spectroscopy (AES), scanning electron microscopy (SEM).
The surface morphology, microstructural properties, phase composition, elemental depth distribution of NiTi after implantation and an analysis of the biocompatibility of these surfaces will be shown.

Keywords: NiTi; surface modified; biocompatibility; plasma ion implantation

  • Lecture (Conference)
    European Vacuum Congress, Berlin, June 23-26, 2003
  • Applied Surface Science 235(2004), 126-131

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Publ.-Id: 5755