Evaluation of physicochemical properties of surface modified Ti6Al4V and Ti6Al7Nb alloys used for orthopedic implants

The paper presents the results of selected functional properties of TiO₂ layers deposited by ALD method on the surface of Ti6Al4V and Ti6Al7Nb alloys intended for implants in bone surgery. TiO₂ layer was applied at the constant temperature of the ALD process at T = 200 °C at a variable number of cycles, which resulted in a different layer thickness. Different process cycles of 500, 1250, and 2500 were analyzed. The application of experimental methods (AFM, SEM, wettability, potentiodynamic test, EIS, scratch test, nanohardness and layer thickness) enabled to select the optimal number of cycles, and thus the thickness of the TiO₂ layer of the most favorable functional properties. The obtained results clearly showed that regardless of the type of titanium substrate, the TiO₂ layer applied in a 2500 cycle ALD process has the best physicochemical and electrochemical properties. These properties have major impact on biocompatibility, and therefore the quality of the final product. The information obtained can be useful for manufacturers of medical devices involved in the production of implants used in reconstructive surgery of skeletal system.