Beitrag zur kinetik der korrosion von Fe in sauren sulfat- und perchloratlösungen

Voigt, C.

doi:10.1016/0013-4686(68)80114-8

Cited by 20 publications

(3 citation statements)

References 35 publications

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“…There are two theoretical values which are most frequently found experimentally. One of these is ba ----2.303 RT/2F (or 0.030V), predicted by the Heusler mechanism (4-6) for reaction [1] Fe + OH-= (FeOH)cAT -{-e- This mechanism, involving adsorbed FeOH as a catalyst, has found independent support (7,8). The other theoretical value is ba ~ 2.303 RT/I.5F (or 0.…”

Section: ] Bamentioning

confidence: 97%

Corrosion Kinetics of Iron in Acid Sulfate Solutions

Barnartt¹

1972

J. Electrochem. Soc.

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The kinetics of anodic iron dissolution and cathodic hydrogen evolution have been studied during the corrosion of four grades of iron: zone‐refined, iron with 0.5 Mn (a/o) or 0.15 Ti added, and Ferrovac E. The titanium, which caused second‐phase particles to accumulate on the surface, and manganese had little effect on iron‐dissolution rates, but both additions inhibited hydrogen evolution significantly. Zone‐refined iron yielded constant Tafel slopes: ba=0.067±0.002 , bc=−0.11 normalto 0.12V . Impurities caused b a and b c to drift to more positive values during corrosion. A new method of analyzing anodic transients is recommended, and this analysis shows that the usual steady‐state polarization curve is an unreliable indicator of reaction mechanism.

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Section: ] Bamentioning

confidence: 97%

Corrosion Kinetics of Iron in Acid Sulfate Solutions

Barnartt¹

1972

J. Electrochem. Soc.

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“…A second group of investigators (18)(19)(20) has observed ba ----30 mV and ZH+ ------2. 3 In the Heusler mechanism which yields this set of parameters, Eq.…”

Section: Zh+ --01oga(h+) Ementioning

confidence: 98%

“…The involvement of OH-ions at the iron/acid interface was first suggested by Bonhoeffer and Heusler (23) to explain the experimental observations that at the same electrode potential, the rate of iron dissolution in acid solutions was less than that in basic solutions (24) and decreased in acid solutions with decreasing pH (25). The generation of OH-ions in acid solutions is presumed to occur by dissociation of water molecules at the electrode surface (1,(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27). In addition, the reaction mechanisms are directed toward production of the species FeOH +, which results from the hydrolysis of ferrous salts and "is present in significant concentrations even in relatively acid media" (28).…”

Section: Zh+ --01oga(h+) Ementioning

confidence: 99%

Kinetics of Iron Corrosion in Concentrated Acidic Chloride Solutions

McCafferty

Hackerman

1972

J. Electrochem. Soc.

147

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The kinetics of active iron dissolution at 25°C has been studied in deaerated 1N and 6N chloride solutions for hydrogen ion concentrations of 0.1–6.0N. For 1N chloride solutions with false[H+false]≤3N , the dissolution reaction is described by anodic Tafel slope bnormala=60 normalmV and electrochemical reaction order with respect to hydrogen ion activity zH+=−1 . These parameters are characteristic of a dissolution mechanism in which chemisorbed halide ions interact with adsorbed hydroxyl ions in a two‐electron rate‐determining step. For 6N chloride solutions, this mechanism holds only over a narrower (H+) region up to 0.24N, in which zH+=−1 . With increased false[H+false],zH+ normalis zero ; and for false[H+false]2.4N,zH+=+2 , indicating that the hydrogen ion (and no longer the hydroxyl ion) catalyzed the dissolution reaction. A positive value of zH+ ensues for synergistic adsorption of hydrogen ions on the halide ion covered surface. A formal detailed dissolution mechanism is proposed, giving zH+=+2 and normalZx−>0 , in agreement with experiment. Alternate dissolution mechanisms including one‐electron transfer schemes are discussed.

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Zum Mechanismus der Reaktionen von Übergangsmetallen mit wasserfreien Monocarbonsäuren

Heitz

1969

Ber Bunsenges Phys Chem

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Die Auflösung von Zink, Eisen, Nickel und Kupfer wird in der Reihe der wasserfreien Monocarbonsäuren C1 bis C4 untersucht, um zu klären, ob der elektrochemische Korrosionsmechanismus in Medien mit abnehmender Dielektrizitätskonstante und dadurch stark sinkender Leitfähigkeit erhalten bleibt. Monocarbonsäuren fungieren als Oxydationsmittel, wobei allerdings nicht der thermodynamisch begünstigte Alkohol, sondern Wasserstoff + Carboxylationen entstehen.Aus der Potentialabhängigkeit der Reaktionsgeschwindigkeit und der Übereinstimmung von elektrochemischen und chemisch analytisch ermittelten Reaktionsgeschwindigkeiten ergibt sich ein elektrochemischer Reaktionsmechanismus, dessen Teilschritte diskutiert werden. Bei der kathodischen Teilreaktion ergibt sich für die Aktivierungsentropie eine Starke Abhängigkeit von der Anzahl der C‐Atome, für die Aktivierungsenthalpie eine nur schwache. Dies läßt auf eine sterische Hinderung durch den Alkylrest schließen. Eine räumliche Behinderung ist auch die Ursache dafür, daß ein Übergangskomplex zwischen einem zweiwertigen Metallatom und zwei Carbonsäuremolekeln nicht existieren kann.Zur Aufhahme der Stromdichte‐Potential‐Kurven in den wenig leitfähigen Medien wird die galvanostatische Unterbrechermethode verwendet. Der Potentialvergleich in den verschiedenen Lösungsmitteln erfolgt über die Ferrocen‐Ferricinium(+)‐Elektrode.

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Beitrag zur kinetik der korrosion von Fe in sauren sulfat- und perchloratlösungen

Cited by 20 publications

References 35 publications

Corrosion Kinetics of Iron in Acid Sulfate Solutions

Corrosion Kinetics of Iron in Acid Sulfate Solutions

Kinetics of Iron Corrosion in Concentrated Acidic Chloride Solutions

Zum Mechanismus der Reaktionen von Übergangsmetallen mit wasserfreien Monocarbonsäuren

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