Corrosion behavior of TiO₂‐coated Ti–6Al–7Nb surfaces obtained by anodic oxidation in sulfuric or acetic acid

Abstract

The morpho-structural and electrochemical properties of the oxide film formed on the implants surface play a decisive role for the bio-compatibility of titaniumbased prosthesis. The aim of the present work is to investigate and compare the corrosion behavior of titanium dioxide (TiO 2 ) coated Ti-6Al-7Nb prepared by anodic oxidation in two different electrolytes (1 M acetic acid (CH 3 COOH) and sulfuric acid (H 2 SO 4 ) solutions) and at two different oxidation potentials. The corrosion behavior of oxidized samples was investigated in Hank's simulated physiological solution, using cyclic polarization method and electrochemical impedance spectroscopy and the obtained results were compared with those recorded on bare Ti-6Al-7Nb in the same experimental conditions. The oxidation in CH 3 COOH was proven to be more beneficial for the corrosion resistance of Ti-6Al-7Nb samples than the oxidation in H 2 SO 4 of same concentration.

Corrosion Resistance of a Plasma-Oxidized Ti6Al4V Alloy for Dental Applications

“…Table 2 shows that for untreated alloy, the outer porous layer resistance, R o , value of 154 ohm cm 2 was obtained. Other studies [15,17,33] have reported values of 333, 800, and 287 ohm cm 2 , respectively, for this alloy in Hank s solution, somehow different to those used in this work. This value increased as the oxidation time increased, reaching a highest value of 59,500 ohm cm 2 for specimen oxidized during 3 h. A further increase in the oxidation time decreased the value for R o .…”

“…On the other side, the inner compact barrier layer resistance value, R i , was 331,000 ohm cm 2 for untreated specimen, whereas other researchers reported values of 551,000, 1.0 × 10 6 , and 6.4 × 10 6 ohm cm 2 , respectively [15,17,33]. Similar to the value for the outer porous layer resistance, R o , the value for R i increased as the oxidation time increased, reaching its highest value for specimen oxidized during 3 h, decreasing for a further increase in the oxidation time.…”

“…Cao [17] oxidized a Ti6Al4V alloy at 700 • C during 5 h in air, and the R o value increased from 333 to 16,000 ohm cm 2 for oxidized specimen. Similarly, Cotolan [33] produced a TiO 2 layer by anodizing a Ti6Al4Nb alloy in sulfuric acid at two potentials, and the value for R o increased from 800 ohm cm 2 for untreated alloy to 3000 and 9000 ohm cm 2 for alloys anodized at 1 V and 3 V, respectively.…”

“…Since corrosion resistance is related to the metal surface properties, one of the ways to improve this property is by altering the alloy surface characteristics. Among the different ways to improve the surface properties, some of the most commonly used methods involve altering the alloying chemical composition, heat treatments chemical vapor deposition (CVD), physical vapor deposition (PVD), ion implantation, solgel coating, anodic oxidation, laser treatment, pack cementation, etc., [22][23][24][25][26][27][28][29][30][31][32][33]. Plasma spray technology has been used to apply coatings on Ti-base alloys to improve their corrosion resistance [34,35].…”

“…Additionally, Cao et al [17] used thermal oxidation, whereas Öteyaka [32] used cryogenic treatments. Cotolan [33] produced a TiO 2 layer by anodizing a Ti6Al4Nb alloy in sulfuric and acetic acids, corroding them in Hank's solution, and found better properties in the ones anodized in acetic acid. However, the use of ions implantation such as oxygen by plasma to produce oxides on the Ti6Al4V alloy has not been reported; thus, the goal of this research work is to evaluate the corrosion resistance of a plasma-oxidized Ti6Al4V alloy in artificial saliva.…”