Mechanical properties of titania films used as biomaterials

We evaluated the nano-hardness, elastic modulus and brittleness of titanium oxide (titania) films produced by anodic oxidation for biomedical applications. These mechanical properties were studied as a function of depth displacement with respect to electrolyte concentration and potential applied to the electrochemical treatment. The measurements were performed by instrumented indentation tests in air. For shallow depths, the nano-indentation results showed that the nano-hardness of the titania films were greater than those for commercially pure Ti (cp-Ti), and that they varied with the applied potential. Also the elastic modulus values were smaller as compared to those of cp-Ti, and they showed to be little influenced by electrolyte concentration and/or applied potential. Some impressions from the nano-indenter tip on the titania films were observed by scanning electron microscopy (SEM). Despite the promising results obtained, namely, hard films with reduced elastic modulus, the SEM images revealed some micro-cracks from indenter impressions in the oxide films produced in H2SO4 at 150 V. These results thus indicate that Ti anodic films on cp-Ti can be applied to the medical field when submitted to low loads (<200 mN).