Electrochemical Properties of Oxide Films on Ti
Authors: Ooniwa Keisuke , Yagi Yuta , Suzuki Ryoji , Noda Kazuhiko 
Published: February 2020

Introduction

Titanium has high corrosion resistance due to existence stable passive film on its surface. Moreover, titanium has biocompatibility and high mechanical strength. Therefore titanium can be used for biomaterial. Not only I generate it by oneself get oxide film to maintain superior corrosion resistance When I use titanium at a practical use stage, but also may put making oxide film before the use. Particularly, it is concerned about corrosion being promoted because a function, a property of the titanium surface changes progressively when a point varying in thickness and the property of a formed film exists. The factors affect in corrosion of metallic material present in the human body. The chloride ion has been performed so far. However there are few reported cases of the influence that the density of NaCl gives to corrosion behavior of titanium.
Therefore the influence of the surface film was evaluation by measuring the current which the catalytic current measurement was performed, and drifted between titanium having a variety of surface. In addition, using the aluminum and zirconium as a comparison 2.
Experimental Methodology

2.1 Polarization curves measurement The sample ware polished titanium, aluminum and zirconium. Test solution was 0.1M NaCl solution. The solution temperature was ambient temperature, and in atmosphere. The potential of the 1800 seconds after dipping start was immersed potential. Counter and the reference electrode was Pt and silver/silver chloride/saturated KCl electrode, respectively. Shifted the potential from the immersion potential to 1.0V. Shift the potential speed was 1mV/s.

2.2 Galvanic corrosion conditions

The samples ware prepared from tow kind of titanium. The first sample was bare titanium which was polished with emery paper. The second sample was titanium which was treated by anodic oxidation treatment. Test solution was 0.1M NaCl solution. The solution temperature was ambient temperature, and in atmosphere. As boric acid anodized – performs 3600s between and polarization at constant potential in a sodium borate buffer solution (pH8.4), to prepare an oxide film on the titanium. Setting potential was 2V, 5V, and 9V. The titanium anodized(titanium(A)), was immersed in 0.1M NaCl in conduction with titanium immediately after the mechanical polishing(titanium(P)), 3600s measuring temporal changes of the current flowing between them. I also was measured for the current flowing between the sample of titanium(P)titanium(P)for comparison.
3.
Result

3.1 Polarization curves measurement

Which sample also nonconductor area has been confirmed.In addition, non-conductor current density was about the same. However, since the aluminum and zirconium sharp rise in current density could be confirmed, it considered to corrosion is occurring. Aluminum rose in current density at lower zirconium potential was confirmed. Titanium increase in current density in the measuring range could not be confirmed. From this result Ti has most safety oxide film.

3.2 Galvanic corrosion conditions

Galvanic corrosion behavior of titanium different oxide film state in 0.1M NaCl solution was evaluated. In any Conditions the micro-cell observation results show the current flows immediately after immersing. However, the current density shifts to approaching zero value and does not flow significantly after a period time.
It can be explained that there is no formation of micro-cell due to passive film after some period time. the effect of anodic oxidation treatment was also observed. The corrosion resistance of the treated sample decreased which was indicated by higher current density in the starting immersion. Moreover, after several time period the current density of the treated sample was still higher than bare titanium even though in small value.
4.Conclusion
・Ti made stability passive film over a wide potential in NaCl Solution.
・The different thickness or the properties of the passive film of Ti, which condition did not make micro-cell.
・In the process about 3600 seconds oxidation in NaCl solution, the effect of Ti was disappeared.