Influence of surface modification on physico-chemical properties of Ti6Al7Nb alloy

- The anodic oxide (E = + 90 V) improves the corrosion resistance of Ti6Al7Nb alloy.
- The surface layer formed at E = + 90 V potential shows low surface wettability.
- Anodic oxidation (E = + 90 V) has a major role in the final quality of the surface layer.

Hemocompatibility of titanium alloys, including Ti6Al7Nb alloy, is increased by e.g. modification of the surface layer by using engineering methods. The methods used to modify the surface layers must ensure repeatability and uniformity of their physical and chemical properties. For this reason, surface layer modification for titanium and its alloys uses low-temperature methods, e.g. anodic oxidation. The authors proposed coating with oxide layers through anode oxidation of Ti6Al7Nb alloy used to manufacture blood-contacting implants. In order to archive improved hemocompatibility of the evaluated alloy, which is closely associated with corrosion resistance and wettability of the surface - criteria for optimum choice of the surface modification option - the following preliminary tests were selected: potentiodynamic, potentiostatic, impedance and wettability as well as surface energy. Additional tests were performed for the best option to ensure complete characteristics of physicochemical and biological properties of the modified surface, i.e. surface topography by atomic force method (AFM), scanning electron microscopy (SEM), metal ion release tests. Anodic oxide (E = + 90 V) improves the corrosion resistance of Ti6Al7Nb alloy in artificial plasma, and also reduces the wettability of the surface. On the basis of the obtained results it may be stated that the variant of surface processing proposed by the authors shows a beneficial effect on improved hemocompatibility of implants used in the circulatory system.

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