Hydrogen transport through thin titanium oxides

Zeng, Yimin; Noël, James J.; Norton, P. R.; Shoesmith, David W.

doi:10.1016/j.jelechem.2010.06.022

Cited by 41 publications

(24 citation statements)

References 57 publications

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“…That may be why we do not observe cathodic currents at potentials positive of −0.4 V SCE , but the fact that we and Zeng et al, 12,39 did observe cathodic currents at potentials more positive than −0.6 V SCE suggests that even without impurities and alloying additions, the presence in the oxide film of electronic defects, vacancies, and disorder at grain boundaries can render the oxide more readily conductive locally.…”

Section: Discussioncontrasting

confidence: 52%

“…This behavior may also account for the discrepancy between the notion that potentials negative of ∼−0.6 V SCE are required for significant and damaging amounts of hydrogen ingress 1,5,8,9,11 and the observation of hydrogen penetration at much more positive potentials in this work and recent others. 12,17,18,39 If local hydrogen absorption windows at grain boundaries become active, but hydrogen ingress is retarded by hydride "plugs" at their base, then the amount of hydrogen absorbed may appear to be inconsequential (e.g., below detection limit) on a bulk Ti material.…”

Section: Discussionmentioning

confidence: 99%

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Hydrogen Absorption into Titanium under Cathodic Polarization: An In-Situ Neutron Reflectometry and EIS Study

Vezvaie¹,

Noël

Tun³

et al. 2013

J. Electrochem. Soc.

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Hydrogen (deuterium) absorption into sputter-coated titanium (Ti) film electrodes during cathodic polarization in heavy water (D 2 O) was monitored using in-situ neutron reflectometry (NR) and electrochemical impedance spectroscopy (EIS). The scattering length density (SLD) of Ti metal increased with increasing cathodic polarization, due to the penetration of deuterium through the surface oxide and into the underlying metal. The rate of D absorption estimated from the NR data showed a pattern with four distinctive regions separated by potential boundaries between −0.35 and −0.4 V SCE and around ∼−0.6 V SCE . EIS results support division of the behavior into these potential ranges. Hydrogen absorption by Ti was observed at potentials <∼−0.35 V SCE , where the capacitance and resistance of the TiO 2 layer dramatically changed. At this point, the D content of the film quickly achieved a level of ∼900 ppm by weight (atom ratio D:Ti ∼ 0.04). Decreased absorption kinetics were observed over the potential region from ∼−0.40 V SCE to −0.6 V SCE , indicating that D absorption was controlled either by a diffusion process through the TiO 2 layer or by the formation of blocking hydrides at the Ti/TiO 2 interface, at the base of the defective locations in the oxide through which the hydrogen was entering. Significant increases in the current density and SLD of the Ti film at potentials more negative than −0.6 V SCE were assigned to widespread hydrogen absorption and TiH x growth within the metal. These observations are consistent with hydrogen ingress through the oxide film, probably via weak points containing electronic defects and disorder, such as grain boundaries and triple points, at potentials as mild as ∼−0.4 V SCE , and with hydrogen penetration through continuous, intact oxide via the previously published redox transformation mechanism, at potentials more negative than −0.6 V SCE . Titanium corrosion processes are often accompanied by hydrogen production. For example, 80% or more of the crevice corrosion process on Ti is driven by the reduction of protons inside the crevice:This leads to the absorption of atomic hydrogen, and can result in extensive hydride formation. 1,2 Cathodic polarization and galvanic coupling with active metals can also cause hydrogen evolution on the Ti surface and hydrogen penetration into the bulk metal. Since hydrogen absorption into Ti structures can lead to their failure by brittle cracking, once the hydrogen concentration achieves a critical level, 3 safe operation of such structures requires a detailed knowledge of the mechanism of hydrogen entry into Ti so that exposure conditions that put the structure at risk of hydrogen-induced cracking can be avoided. A number of studies have been done on the physicochemical properties of Ti/H systems, as well as on hydrogen-induced cracking of Ti.3,4 Here we explore the role of the electrochemical potential in determining whether adsorbed hydrogen atoms generated by water reduction can penetrate the native oxide on Ti.The surface oxide layer play...

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Section: Discussioncontrasting

confidence: 52%

Section: Discussionmentioning

confidence: 99%

Hydrogen Absorption into Titanium under Cathodic Polarization: An In-Situ Neutron Reflectometry and EIS Study

Vezvaie¹,

Noël

Tun³

et al. 2013

J. Electrochem. Soc.

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“…Hydrogen permeation through titanium oxide film is a very complex process involving interfacial charge transfer, trapping, and transport, thus is inherently influenced by properties of the oxide, such as the chemical composition and structure [14]. Several studies [15,16] have shown that diffusion of hydrogen in TiO 2 is much slower than in Ti metal.…”

Section: Discussionmentioning

confidence: 99%

Study of Oxidation of Thin Ti Film Controlled by Reduction Processes in Water Vapor Plasma

Urbonavičius

Pranevičius

Tučkutė

et al. 2012

e-J. Surf. Sci. Nanotech.

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Changes of microstructure, phase composition and surface morphology were investigated for 200-700 nm thick Ti films, which were deposited on Si substrates using magnetron sputtering technique and treated at pressure of 5-10 Pa by water vapor plasma with the plasma processing power in the range of 20-300 W. Depth profiling of oxygen and hydrogen atoms across the thickness of plasma treated Ti films, surface height nanotopography and four-point probe resistivity measurements have been performed complementary to the analysis of phase and compositional changes registered by XRD and EDS techniques, respectively. It is shown that the different reduction/oxidation state on the surface can be maintained by coordinated adjustment in plasma power. Due to strong coupling of adsorbed water clusters to hydrophilic titanium oxide, a fast and complete transformation of Ti into TiO2 accompanied by film cracking and spontaneous lifting in the form of "popping off" discrete blisters was observed. Analysis of the experimental results is used to obtain important insights on the behavior of water molecules adsorbed on the reduced titania surfaces exposed to water vapor plasma at room temperature.

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“…Quantificationally, the hydrogen diffusion coefficient in pure titanium is 1.07 Â 10 À12 cm 2 /s, however that value in TiO 2 is only 7.5 Â 10 À20 cm 2 /s [27]. Consequently, the hydrogen atoms will first be absorbed by the TiO 2 , even composing metastable compounds TiO(OH) [Equation (9), [28]] if their contents continuously increase. Then, Zeng et al [28] thought that the hydrogen atoms in TiO(OH) will serve as the electron donors to produce hydrogen ions, the reverse reaction of Equation (8).…”

Section: Macroscopic Morphologiesmentioning

confidence: 99%

“…Consequently, the hydrogen atoms will first be absorbed by the TiO 2 , even composing metastable compounds TiO(OH) [Equation (9), [28]] if their contents continuously increase. Then, Zeng et al [28] thought that the hydrogen atoms in TiO(OH) will serve as the electron donors to produce hydrogen ions, the reverse reaction of Equation (8). However in our opinion, these hydrogen atoms will be mutually coupled and form hydrogen gases H 2 , Equation (10).…”

Section: Macroscopic Morphologiesmentioning

confidence: 99%

Failure analysis of leakage on titanium tubes within heat exchangers in a nuclear power plant. Part I: Electrochemical corrosion

Yang

Gong

Yuan

2011

Materials & Corrosion

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Titanium tubes generally exhibit superior resistance against electrochemical corrosions amid seawater for their passive films TiO 2 . However, hydrogenassisted corrosion (HAC) is actually the Achilles' heel to titanium materials when the temperature exceeds near 70 8C. In this event, severe degradations like quick thinning and leakage were frequently detected on a large number of titanium tubes exposed to natural seawater environment within heat exchangers in a nuclear power plant, which caused serious safety problems. This paper is the Part I of totally two parts conducted for the whole failure analysis study, mainly focusing on electrochemical aspect of failure causes and their behaviors. By means of over ten kinds of characterization methods, the analysis results identified that the HAC induced by the interaction effects between galvanic corrosion and crevice corrosion led to local bulges of the inner walls of some titanium tubes, and then the bulges were quickly thinned and eventually ruptured under the eddy erosion from the seawater containing sediment particles. Finally, relevant mechanisms were addressed in detail and prevention methods were proposed as well.

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Hydrogen transport through thin titanium oxides

Cited by 41 publications

References 57 publications

Hydrogen Absorption into Titanium under Cathodic Polarization: An In-Situ Neutron Reflectometry and EIS Study

Hydrogen Absorption into Titanium under Cathodic Polarization: An In-Situ Neutron Reflectometry and EIS Study

Study of Oxidation of Thin Ti Film Controlled by Reduction Processes in Water Vapor Plasma

Failure analysis of leakage on titanium tubes within heat exchangers in a nuclear power plant. Part I: Electrochemical corrosion

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