Prevention of Hydrogen Absorption of Titanium by its Surface Oxidizing

Abstract

The effect of surface treatment of titanium on hydrogen absorption was investigated.Surface treated titanium specimens prepared by polishing, anodizing and air oxidizing were immersed in 0.5-6%HCl solutions at the temperature range of 70C to 250C. After immersion, the weight loss, hydrogen content and oxide film thickness of three specimens were measured. As a result, it became clear that anodizing did not reduce hydrogen absorption of titanium because titanium oxide film formed by anodizing had dissolved away in dilute HCl solutions for short time but air oxidizing specimen was stable in this solution for long time and so prevented to hydrogen absorption of titanium.These results of laboratory tests corresponded to the results of field tests conducted in hot molten urea and reducing acid solution at high temperature.

Some Results on the Electrochemical and Thermal Oxidation and the Electrochemical Oxygen Evolution at Ti x Cu1 − x Alloys

“…The thickness of the mixed Ti oxide-Cu layer is estimated to be about 900h. This value is much higher than the value for an oxide layer of pure TiO2 prepared under comparable oxidation conditions (-200h) (22). This is in qualitative agreement with results obtained from marker experiments, where Au doping of the Ti surface impedes the dissolution process of the oxide layer into the bulk and therefore causes an increase in oxide layer thickness (23).…”

Cathodic Reduction of Anodic Oxide Films Formed on Titanium

“…Under the open-circuit condition, however, the anodic oxide film was gradually thinned at a rate of I nm/h. The results indicate that the anodie oxide film mainly composed of Ti(IV) oxide reductively dissolves to form Ti(III) ions in acidic solution TiO2 + 4H + + e -* Ti3+a,, + H20 [2] In an induction period observed in the initial stage of reduction, no titanium ion is found in the solution, as shown in Fig. 2.…”

“…TiO2 + 4H + + e -* Ti3+a,, + H20 [2] In an induction period observed in the initial stage of reduction, no titanium ion is found in the solution, as shown in Fig. 2.…”

“…Fukuzuka et al (2) have pointed out that the oxide film formed by air oxidation at elevated temperatures acts as a barrier against the hydrogen absorption into the titanium metal but that the oxide film anodically formed loses its barrier property during cathodic reduction in a time period shorter than that of the air oxidation film. Dyer et al (3) have suggested that hydrogen can be absorbed by the anodie oxide film in the hydrogen evolution potential region and that hydrogen in the oxide film can be reversibly desorbed in the anodic potential region.…”

Ex situ TEM observation of localized attack on AA 6061

“…Additional information is required about the electrochemical behavior of the intermetallics. Many papers were published on the electrochemistry of different binary phases [13][14][15][16] or the ternary phase [17,18] intermetallics on pitting corrosion. However, the determination of the particle structure and evaluation of their corrosion behavior is usually independent.…”