In this paper, the TiO 2 coatings were performed on pure Ti at 20, 5 and -10 o C and on Ti6Al4V alloy at 20 and -10 o C by Micro-Arc Oxidation (MAO) process. The treatments were performed in an electrolyte containing 1.8 M H 2 SO 4 /0.4 M H 3 PO 4 and applied voltage of 180 V. The SEM results from the surface morphologies of coatings indicated that unlike the volcanic morphology of oxide layers on pure Ti, a cortex-like morphology with irregular vermiform slots was seen on MAO/Ti6Al4V samples. Additionally, the pores were sealed in sub-zero spark anodized pure Ti samples. The EIS analysis showed that MAO coatings were composed of a double layered oxide film consisting of a porous outer layer and a barrier inner layer. The simulated data from the electrical–equivalent circuit model illustrated the higher resistance of both porous and barrier layers in MAO coatings performed at -10 o C. The polarization curves confirmed the higher corrosion resistance of these coatings. Tribocorrosion results illustrated that the potential drop values of untreated samples was significantly increased by MAO process. In addition, the tribocorrosion resistance of coatings on Ti6Al4V alloy was higher than that on pure Ti. SEM images of the worn surfaces demonstrated the local detachment of oxide layer within the wear track of MAO coatings performed at 20 and 5 o C. Conversely, no delamination was detected in MAO/Ti/-10 and a mild abrasive wear was the dominant mechanism. The TiO 2 /nano-HA composite coating was performed in-situ by MAO process. The results showed the low corrosion and passive current density of the nanocomposite coating. According to the presence of Ca in TiO 2 /nano-HA coating confirmed by EDS analysis, this nanocomposite coating could be a good candidate for biological applications. Keywords: Micro–Arc Oxidation, Pure Ti, Ti6Al4V, Corrosion, Tribocorrosion, TiO 2 /nano-HA composite coating
