Dissolution and Passivation of Stainless Steels Eposed to Hydrochloric Acid

Wegrelius, L.; Olefjord, I.

doi:10.4028/www.scientific.net/msf.185-188.347

Cited by 23 publications

(19 citation statements)

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“…As a tendency the film thickness in pure 0.1 M NaCl solution was slightly lower. l In agreement with previous results obtained in neutral [10,11,17] and acidic solutions [12,19], the substrate immediately beneath the passive film is strongly enriched in metallic nickel for all alloys (about twice the bulk content) and depleted in iron ( 6).…”

Section: Quantitative Evaluationsupporting

confidence: 90%

Surface analytical and electrochemical study on the role of adsorbed chloride ions in corrosion of stainless steels

Rossi

Tulifero

Elsener

2001

Materials and Corrosion

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Section: Quantitative Evaluationsupporting

confidence: 90%

Surface analytical and electrochemical study on the role of adsorbed chloride ions in corrosion of stainless steels

Rossi

Tulifero

Elsener

2001

Materials and Corrosion

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“…It has been reported that the faradaic impedance due to metal dissolution at the oxide film/electrolyte interface depends strongly on the anion type, together with the local pH at the passive film [27]. In this respect, it has been shown [28][29][30][31][32] that Cl ) ions are incorporated in the passive layer when the passivation is performed in Cl ) containing electrolyte. Also, surface analysis results by Hubschmid et al [33] showed that films grown in chloride containing sulphate solution incorporate the two electrolyte anions.…”

Section: Eis Measurementsmentioning

confidence: 96%

Stability of spontaneous passive films on high strength Mo-containing stainless steels in aqueous solutions

2007

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The stability of naturally grown passive films on some Mo-containing stainless steel specimens was examined in aerated and deaerated universal buffer solutions with different pH (2-12) as well as in sulphate and chloride solutions. Open circuit potential (E oc ) and electrochemical impedance spectroscopy (EIS) were used as measuring techniques. In all cases, E oc shifts towards less negative values with time until the potential reaches its steady-state (E ss ) value. The E ss value is found to be more positive with decrease in solution pH or increase in Mo content in the alloy and becomes less positive in deaerated buffer solutions. Also, the thickening rate of the outer layer for the duplex passive film increases with increasing extent of Mo in the steel substrate or pH of the test solution. For a given alloy, E ss decreases linearly with the anion concentration (C), and is always more positive in Cl ) than in SO 4 2) media for C ‡ 0.05 M. Analysis of the EIS data showed that the total resistance (R T ) of the passive film has higher values in aerated solutions, and is generally lower in basic solutions. This indicates that lower solution pH favours the formation of oxide films offering better protection. Furthermore, the higher values of R T in Na 2 SO 4 solutions suggest the formation of more stable passive films in sulphate than in chloride solutions. This is discussed on the basis of the relative degree of anion incorporation into the passive films.

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“…This mainly amorphous Cr(III) hydroxide may have been the compound previously shown to build the passive oxide layer on steels and Ni-based alloys with Cr contents > ~ 12%, which is stable under these conditions. [17][18][19][20] With increasing temperature, the transpassive potential of Cr and Mo was exceeded, and both metals were oxidized to their hexavalent compounds, molybdate (MoO 4 2-) and dichromate (Cr 2 O 7 2-), or CrO 4 2-, respectively (Equation [1]). [21][22] Mo is known to be in the transpassive state at much lower potentials than Cr.…”

Section: Corrosion Engineering Sectionmentioning

confidence: 99%

Corrosion of Alloy 625 in Aqueous Solutions Containing Chloride and Oxygen

Kritzer¹,

Boukis²,

Dinjus³

1998

CORROSION

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Alloy 625 (UNS N06625) is used frequently as a reactor material for the oxidation of hazardous organic wastes in supercritical water (supercritical water oxidation [SCWO]). In the presence of chloride (Cl -) and oxygen (O 2 ), all Ni-based alloys corrode fast in high-temperature, subcritical water. High-pressure, high-temperature-resistant tube reactors made of alloy 625 were used as specimens. Coupons were exposed simultaneously inside the test tubes. Experimental conditions included temperatures up to 500°C and pressures up to 38 MPa. Pitting corrosion was observed at temperatures above ≈ 130°C to 215°C. At higher temperatures (up to the critical temperature of water), transpassive dissolution dominated. Under certain conditions, transgranular stress corrosion cracking (TGSCC) appeared in the transition zone between the passive and transpassive regions leading to premature failure of the test reactors. Parts of the corrosion products were insoluble in supercritical water and formed thick layers in the supercritical part of the reactor. Underneath these layers, very little intergranular corrosion (IGC) occurred. In neutral or alkaline solutions and in deaerated hydrochloric acid (HCl), corrosion rates of transpassive dissolution decreased drastically.

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Dissolution and Passivation of Stainless Steels Eposed to Hydrochloric Acid

Cited by 23 publications

References 0 publications

Surface analytical and electrochemical study on the role of adsorbed chloride ions in corrosion of stainless steels

Surface analytical and electrochemical study on the role of adsorbed chloride ions in corrosion of stainless steels

Stability of spontaneous passive films on high strength Mo-containing stainless steels in aqueous solutions

Corrosion of Alloy 625 in Aqueous Solutions Containing Chloride and Oxygen

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