Electrochemical Anodizing Treatment to Enhance Localized Corrosion Resistance of Pure Titanium

Abstract

Background: Titanium has outstanding corrosion resistance due to the thin protective oxide layer that is formed on its surface. Nevertheless, in harsh and severe environments, pure titanium may suffer localized corrosion. In those conditions, costly titanium alloys containing palladium, nickel and molybdenum are used. This purpose investigated how it is possible to control corrosion, at lower cost, by electrochemical surface treatment on pure titanium, increasing the thickness of the natural oxide layer. Methods: Anodic oxidation was performed on titanium by immersion in H 2 SO 4 solution and applying voltages ranging from 10 to 80 V. Different anodic current densities were considered. Potentiodynamic tests in chlorideand fluoride-containing solutions were carried out on anodized titanium to determine the pitting potential. Results: All tested anodizing treatments increased corrosion resistance of pure titanium, but never reached the performance of titanium alloys. The best corrosion behavior was obtained on titanium anodized at voltages lower than 40 V at 20 mA/cm 2. Conclusions: Titanium samples anodized at low cell voltage were seen to give high corrosion resistance in chloride-and fluoride-containing solutions. Electrolyte bath and anodic current density have little effect on the corrosion behavior.

Chemical oxidation as repairing technique to restore corrosion resistance on damaged anodized titanium

“…The easiest and cheapest treatment to adjust oxide layer is anodic oxidation. It consists in applying an anodic polarization of several tens of volts to the metal, promoting the growth of a compact, adherent and corrosion resistant oxide with thicknesses ranging from about 40 nm with anodizing potential 10 V, to about 250 nm at 100 V. [22][23][24] However, in case of already installed part, localized treatment, small part or complex geometry, anodic oxidation could be un-feasible. In these cases chemical oxidation would be suitable to provide the corrosion resistance enhancement needed.…”

Corrosion of titanium: Part 2: Effects of surface treatments

“…The main parameters affecting the characteristics of the resulting oxides are as follows (19,26,27): Increasing the current density of anodization accelerates the oxidation rate and increases the amount of oxide converted from an amorphous state to anatase or even rutile crystalline structure (28), as shown in Figure 1.…”

“…The main parameters affecting the characteristics of the resulting oxides are as follows (19, 26, 27):…”

Laser‐Induced Color Marking of Titanium: A Modeling Study of the Interference Effect and the Impact of Protective Coating

“…Numerous studies concerning various aspects of the laser-induced color marking of titanium as well as stainless steel have recently been published. In these papers, detailed characterizations of optical properties [3][4][5][6][7][8][9], changes in physicochemical properties [3,5,6,[8][9][10][11], oxide thicknesses [3][4][5][6]8] and corrosion resistance [12][13][14][15] were conducted. It has also been found that a number of different process parameters such as laser power, scanning speed of the material, the size of the marked area, the temperature, and position of the sample exert a significant impact on the reproducibility of the resulting color [4].…”