Vol.26, No.1, 2026, pp. 38–47
https://doi.org/10.69644/ivk-2026-01-0038

In order to optimise surface characteristics, corrosion and scratch damage, as important factors for accepting a metallic implant at conditions of a human body, commercially pure titanium (cpTi) can be modified by different treatments, including high pressure torsion (HPT) and anodic oxidation (AO). Here, a nanotube oxide layer on the surface of ultrafine-grained commercially pure titanium (UFG cpTi) is formed using AO in 1M H₃PO₄ + NaF solution during 60 min. SEM microphotographs show that AO with selected parameters can lead to the formation of a highly regular oxide layer with nanotubes on the surface of UFG cpTi. Determination of the surface contact angle shows that the surface of UFG cpTi after AO is more hydrophilic than before AO treatment. In order to characterise the surface topography and adhesion of formed nanotubes, scratch testing on the UFG cpTi surface after AO treatment is done. Corrosion resistance is tested in Ringer's solution with pH value of 5.5 at 37 °C to simulate the environment in the human body. UFG cpTi before and after AO is analysed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation. The inner barrier and outer porous surface layers are highly resistant with capacitive behaviour for both tested materials, but the synergistic action of HPT and AO treatments led to improved corrosion resistance and therefore a reduced corrosion rate for commercially pure titanium in the conditions of the human body.

Keywords: • anodic oxidation • corrosion resistance • high pressure torsion • ultrafine-grained titanium • scratch test