| The objective of this study is therefore to evaluate the potential of a TiNi50.8% single crystal as a biomaterial. The single crystals used are in the orientation <001> and have undergone 4 different heat treatments in a helium atmosphere in order to modify their superelasticity. The mechanical properties drastically change from an orientation to the other. Therefore collaborators from the laboratory of physics and plasticity of the Siberian Institute of Tomsk took in charge the mechanical characterization of different orientations in order to determine which orientation satisfies a given application. From a biocompatibility point of view, we are expecting that the single crystal will be similar or superior to the one of the polycrystals.; Thus the biocompatibility of 50.8%Ni-Ti single crystals has been evaluated in two ways. First we carried out corrosion tests using the cyclic polarization method in a physiological Hank's solution on mechanically polished samples because this method is particularly suitable to detect pitting corrosion. Secondly we studied the effect of corrosion on the oxide layer evolution by determining its composition and its thickness with Auger spectroscopy. Finally, we evaluated the in vitro biocompatibility of the NiTi single crystals. (Abstract shortened by UMI.)... |
