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The following chapter gives an overview of the anodic layers and nanotubes produced with plasma electrolytic oxidation. An introduction into the mechanisms involved in producing these nanofilms, such as the required processing parameters including voltage, current, and time, are discussed. In addition to an examination into the relation and the requirements for a good interface between the implant using these nanofilms and the bone, we also investigate and discuss the available commercial implants employing nanofilms. Commercial applications have enormous potential and are an area of interest for future work. Finally, we discuss the mechanical properties and the improvements obtained on these nanofilms by the scientific community.

Porous TiO 2 coatings were produced on commercially pure Ti substrates by micro-arc oxidation (MAO) in 1.0 M H 2 SO 4 electrolyte for different anodizing times. Their mechanical properties were assessed by means of instrumented indentation, XRD residual stress measurements and scratch resistance tests. The rutile/anatase ratio increased from ~ 0 up to 84% in the 10–360 s anodizing time range, with further increase of coating thickness, porosity and roughness. Titania coatings produced for 180 and 360 s had poor adhesion and uneven surfaces with spontaneous detachment from the substrate. Coating hardness ranged from 3.5 up to 4.0 GPa (close to Ti), whereas the effective elastic modulus varied from 110 up to 120 GPa (19% lower than Ti), regardless of the substrate effects. Coatings exhibited tensile residual stresses, while the substrate compressive stress increased forming a plateau at about − 110 MPa for anodizing time longer than 60 s. The presence of such hardened layer beneath the interface improved the coating integrity in the scratch tests under the severe tribological condition, thereby increasing about tenfold the detachment critical load for the samples prepared in the 10–60 s MAO time range. Therefore, the 60 s anodizing time can be a useful reference line for producing mechanically resistant porous titania coatings.