Comportement anodique du titane dans l'acide chlorhydrique 8 M.l<sup>— 1</sup> désaère. Mécanisme de dissolution-passivation. Influence des conditions hydrodynamiques, du potentiel et de la température

Frayret, J.P.; Caprani, A.; Delrey, François; Moreau, A.; Pointeau, R.

doi:10.1051/jcp/1981780233

Cited by 5 publications

(2 citation statements)

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“…6͒. 30,43 It is coherent with the current-potential ͑I, E͒ profiles. If we exclude the mixed zone close to the corrosion potential, the passivity plateau coincides with the presence of a unique valence 4, as it is the case for very acidic solutions (pH Ͻ 0).…”

Section: Resultsmentioning

confidence: 71%

“…In fact, valences 1 and 2 could never be detected experimentally in solution, 49,50 and no solid compound associated to the corresponding oxidation numbers could either be observed. Therefore, in the domain of existence of valence 4, titanium is covered in a more or less pronounced way by a titanium oxide (TiO 2 ) film depending on the potential and the medium: 14,43,51,52 ͓Ti͑IV͒ ads ͔ ϵ TiO 2 . These results indicate the existence of two very fast first steps with very short lifetime adsorbats ͓Ti͑I͔͒ ads and Figure 5.…”

Section: Discussionmentioning

confidence: 99%

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Titanium Dissolution-Passivation in Highly Chloridic and Oxygenated Aqueous Solutions

Frayret

Botella

Jaszay

et al. 2004

J. Electrochem. Soc.

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The principal objective of this paper is to show that we developed an experimental setup and a dissolution-passivation monitoring technique for use in super critical water oxidation ͑SCWO͒ conditions (T Ͼ 374.15°C, P Ͼ 22 MPa͒. The principal barrier to this technology development is the corrosion of the reactor materials. High corrosion rates were experienced in industrial plants. A major goal is to develop effective tools to determine and control the electrochemical and corrosion parameters. Until now, electrochemical data concerning metallic materials submitted to aqueous solutions at pressures and temperatures beyond the critical point are scarce. This research, in the context of organic wastes SCWO, first proposes, for both sub and supercritical conditions, technical solutions for an electrochemical cell able to give access to quantitative electrochemical information in aggressive solutions (pH у 1.5 and chloride ions content of 1 g/L͒. Its second purpose is to obtain information on a titanium alloy ͑T60 grade͒ behavior in such conditions. The present study leads to a model establishing a reaction mechanism, which operates under normal conditions of pressure and temperature and can be extended to supercritical ones. The limits of use of this material as a plant reactor material for supercritical water oxidation ͑SCWO͒ are evaluated.Supercritical water oxidation ͑SCWO͒ is a high-efficiency, thermal oxidation process capable of treating a wide variety of hazardous and nonhazardous wastes. 1-12 The SCWO reaction takes place at elevated temperatures and pressures above the critical point of water (Pc ϭ 22.1 MPa, Tc ϭ 374°C). Supercritical water ͑SCW͒ under these conditions undergoes a drastic alteration of its density, dielectric constant, hydrogen bonding, and other physical properties. It behaves as a moderately polar liquid under ambient conditions 13 and due to its low dielectric constant, presents very low solubilizing properties for inorganic salts. SCWO processing setups are fully enclosed and do not produce hazardous air pollutants ͑HAPS͒. In a traditional SCWO waste treatment system, dilute aqueous organic waste ͑generally with less than 10% organic wastes͒ is combined with an oxidizer at elevated pressure and temperature ( P Ͼ 22.1 MPa, T Ͼ 400°C) in a reactor for short residence times ͑10-15 s͒. At supercritical conditions, the reactants form a homogeneous single-phase mixture facilitating complete reaction. For most wastes, these conditions are sufficient to achieve 99.99% destruction. However, the high-temperature environment within SCWO reactors and processing systems present significant reliability and performance problems. Experiences have shown that corrosion rates can be rapid when treating wastes containing halogens, such as chlorine. [14][15][16][17][18] The most common corrosion-resistant alloys 19 such as ironbased 10,11 or nickel-based ones 9,10,12,19-22 do not provide adequate protection against chloride attack under the oxidizing conditions performed in SCWO systems. Recently, SCWO reacto...

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Section: Resultsmentioning

confidence: 71%

Section: Discussionmentioning

confidence: 99%

Titanium Dissolution-Passivation in Highly Chloridic and Oxygenated Aqueous Solutions

Frayret

Botella

Jaszay

et al. 2004

J. Electrochem. Soc.

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ChemInform Abstract: ANODIC BEHAVIOR OF TITANIUM IN DEAERATED 8M HYDROCHLORIC ACID. DISSOLUTION‐PASSIVATION MECHANISM. INFLUENCE OF HYDRODYNAMIC CONDITIONS, OF POTENTIAL AND TEMPERATURE

Frayret¹,

Caprani²,

Delrey³

et al. 1981

Chemischer Informationsdienst

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Influence of surface segregation of sulphur on the corrosion resistance of 270 nickel in acidic and alkaline media

Rabu

Saindrenan²,

Caprani

et al. 1992

J Appl Electrochem

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Comportement anodique du titane dans l'acide chlorhydrique 8 M.l^{— 1} désaère. Mécanisme de dissolution-passivation. Influence des conditions hydrodynamiques, du potentiel et de la température

Cited by 5 publications

References 0 publications

Titanium Dissolution-Passivation in Highly Chloridic and Oxygenated Aqueous Solutions

Titanium Dissolution-Passivation in Highly Chloridic and Oxygenated Aqueous Solutions

ChemInform Abstract: ANODIC BEHAVIOR OF TITANIUM IN DEAERATED 8M HYDROCHLORIC ACID. DISSOLUTION‐PASSIVATION MECHANISM. INFLUENCE OF HYDRODYNAMIC CONDITIONS, OF POTENTIAL AND TEMPERATURE

Influence of surface segregation of sulphur on the corrosion resistance of 270 nickel in acidic and alkaline media

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Comportement anodique du titane dans l'acide chlorhydrique 8 M.l— 1 désaère. Mécanisme de dissolution-passivation. Influence des conditions hydrodynamiques, du potentiel et de la température

Cited by 5 publications

References 0 publications

Titanium Dissolution-Passivation in Highly Chloridic and Oxygenated Aqueous Solutions

Titanium Dissolution-Passivation in Highly Chloridic and Oxygenated Aqueous Solutions

ChemInform Abstract: ANODIC BEHAVIOR OF TITANIUM IN DEAERATED 8M HYDROCHLORIC ACID. DISSOLUTION‐PASSIVATION MECHANISM. INFLUENCE OF HYDRODYNAMIC CONDITIONS, OF POTENTIAL AND TEMPERATURE

Influence of surface segregation of sulphur on the corrosion resistance of 270 nickel in acidic and alkaline media

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Comportement anodique du titane dans l'acide chlorhydrique 8 M.l^{— 1} désaère. Mécanisme de dissolution-passivation. Influence des conditions hydrodynamiques, du potentiel et de la température