Long-term behaviour of AISI 304L passive layer in chloride containing medium

Abreu, C.M.; Cristóbal, M.J.; Losada, Ricardo; Nóvoa, X.R.; Peña, G.; Pérez, M.C.

doi:10.1016/j.electacta.2005.06.040

Cited by 95 publications

(65 citation statements)

References 16 publications

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“…2c) (Fe2p spectra for specimens R, C, A1 and B1) is the following: the most intensive peak for Fe is the one for the corroding specimen C, shifted towards lower binding energy, corresponding to Fe 2þ in FeO at 709.2 eV, while for the protected specimens A1 and B1, the corresponding peaks are at 710.2 eV for Fe 3 O 4 or a-Fe 2 O 3 , which is consistent with the observations according the O1s spectrum. For the corroding specimen C, binding energies 709.2 eV and 709.5 eV correspond to FeO and Fe 2 O 3 respectively; for the protected specimens, binding energy 710.2 eV and 710.4 eV correspond to Fe 3 O 4 , the shoulder peaks at 712 eV correspond to FeOOH [25,26]. An example of a fitted spectrum is depicted in Fig.…”

Section: Resultsmentioning

confidence: 99%

The beneficial secondary effects of conventional and pulse cathodic protection for reinforced concrete, evidenced by X‐ray and microscopic analysis of the steel surface and the steel/cement paste interface

Koleva¹,

Guo²,

Breugel³

et al. 2009

Materials & Corrosion

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The present study reports on the investigation of conventional and pulse cathodic protection (CP), in terms of steel surface analysis and investigation of the product layers at the steel/cement paste interface, after a long term (460 days) of conditioning and monitoring. The techniques used were: X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM) and Energy‐dispersive X‐ray (EDX). Wet chemical analysis was used as supportive evidence for ion concentrations in the vicinity of the steel re‐bars. Generally, CP promotes beneficial secondary effects i.e. enhanced OH− concentration and reduced Cl− concentration near the steel surface. Cathodic polarization also results in additional deposition of portlandite, which stabilizes the protective properties of the product layer on the steel surface. Consequently, the fundamental mechanisms, underlying the efficiency of CP techniques in reinforced concrete, are strongly related to beneficial secondary effects of CP, affecting the morphology and transformations of these product layers. Since the experimental evidences to support the aforementioned beneficial effects are rather limited, this study investigates the morphology and composition of the “naturally” formed steel surface layers, along with the properties of the steel/cement paste interface, on corroding and protected steel reinforcement (in comparison to reference, non‐corroding, non‐protected conditions) after 460 days of conditioning. For the corroding specimens, the formation and substantial deposition of voluminous corrosion products, with low adherence to the steel surface is relevant (low protective ability), whereas in the protected specimens, a compact and adherent product layer of more stable high valent iron oxides, or calcium substituted such, was observed. To this end, the present work provides the experimental evidence for the fundamental mechanisms, related to the otherwise recognized positive secondary effects of CP in reinforced concrete.

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Section: Resultsmentioning

confidence: 99%

The beneficial secondary effects of conventional and pulse cathodic protection for reinforced concrete, evidenced by X‐ray and microscopic analysis of the steel surface and the steel/cement paste interface

Koleva¹,

Guo²,

Breugel³

et al. 2009

Materials & Corrosion

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“…7 As already described above, this film is layered in character and can undergo a variety of transformations, depending on the adjacent medium. 5,8,14,15 One of the possible interactions is that chloride anions adsorption enables new charge exchange pathways, which allow the steel surface to corrode. 6 The occurrence of these new charge exchange pathways, could be one of the most likely mechanisms of chloride induced corrosion in reinforced concrete.…”

Section: Review Of Some Fundamental Mechanismsmentioning

confidence: 99%

Investigation of Corrosion and Cathodic Protection in Reinforced Concrete

Koleva¹,

Wit

Breugel³

et al. 2007

J. Electrochem. Soc.

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The present study explores the formation of corrosion products on the steel surface ͑using as-received low carbon construction steel͒ in reinforced concrete in conditions of corrosion and subsequent transformation of these layers in conditions of cathodic protection ͑CP͒. Of particular interest was to investigate whether the introduced pulse CP ͑a cost-effective alternative to CP͒ will lead to similar or even more favorable conversion of the product layers on the steel surface, compared to conventional techniques. Qualification and quantification of the studied layers was performed using X-ray diffraction, X-ray photoelectron spectroscopy, and energy dispersive analysis, visualization of morphology and products distribution was achieved using environmental scanning electron microscopy. The steel surface was found to be covered by a layered, nonhomogeneous formation of products, differing in crystallinity and composition, comprising an inner layer, similar to Fe 3 O 4 , and an outer layer, composed of iron ͑oxy͒hydroxides and iron ͑oxy͒hydroxy-chlorides ͓i.e., a combination of ␣-, ␤, ␥-FeOOH, Fe͑O,OH,Cl͒, and Fe 2 O 3 ͔. The product layer in corroding specimens is a combination of low valent oxides and iron-oxy͑hydroxy͒chlorides, exhibiting a relatively rough morphology. The product layers in the protected specimens were far more compact. Cathodic protection reduces salinity around the steel bars, hence the inner product layer ͑mostly Fe 3 O 4 ͒ remains more uniform, whereas the outer layer exhibits reduced crystallinity. The favorable transformation phenomena were found to be more apparent under pulse CP conditions, attributed to the obviously beneficial effects of pulse CP in terms of enhanced chloride withdrawal from the steel surface and minor influence ͑less side effects͒ on the bulk concrete microstructure. The most common and important causes for reinforcement corrosion are either localized depassivation of the steel surface due to chloride ingress or more uniform corrosion due to acidification of the pore solution as result of carbonation of the cement paste. Cathodic protection ͑CP͒ has been found to be one of the most useful techniques for inhibiting chloride-induced corrosion in reinforced concrete.1 The fundamental mechanisms underlying the efficiency of CP techniques are strongly correlated to the morphology and transformations of product layers on the steel surface. The steel reinforcement used in the present study was as-received construction steel FeB500HKN ͑rebars, d = 12 mm, C Ͻ 0.22 wt %. Electrochemical impedance spectroscopy ͑EIS͒, polarizations resistance ͑PR͒ method, and potentio-dynamic polarization ͑PDP͒ were used for a comparative analysis of electrochemical parameters and corrosion behavior of the embedded steel in the reinforced concrete specimens presented here, in the relevant conditions of corrosion and CP, and the outcomes were reported previously.2 This paper pursues exploration of the formation, distribution, and morphological alterations of corrosion products in the reinforced c...

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“…In this medium, the transformations in the oxide layer lead to a nonhomogeneous dissolution of the passive layer 6 promoting the onset of pitting corrosion.…”

Section: Discussionmentioning

confidence: 99%

“…(1) The formation of Fe 3C hydrated species in the external part of the film 6 (2) The detection of Ni 2C ions in the film formed in NaOH. Ni 2C is not present in the air-formed structure (transformed into Ni 3C at the outermost layer) (3) The slight increase in Cr 3C after cycling Consequently, as the evolution in NaOH takes place, the film transforms from the initial magnetite-type structure 5 to a more hydrated and less conductive layer.…”

Section: Discussionmentioning

confidence: 99%

Effect of surface preparation on the evolution of the passive films formed on AISI 304L

Abreu

Cristóbal

Losada

et al. 2006

Surface & Interface Analysis

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In this work, an insight into the effect of surface roughness in the composition and evolution of the oxide film electrogenerated on an austenitic stainless steel substrate is presented. The obtained results point out the importance of Ni on the oxide layers formed in alkaline media, which can condition their resistance to chloride attack. Polished samples show better corrosion performance than abraded ones owing to Ni enrichment at the metal-oxide interface.

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Long-term behaviour of AISI 304L passive layer in chloride containing medium

Cited by 95 publications

References 16 publications

The beneficial secondary effects of conventional and pulse cathodic protection for reinforced concrete, evidenced by X‐ray and microscopic analysis of the steel surface and the steel/cement paste interface

The beneficial secondary effects of conventional and pulse cathodic protection for reinforced concrete, evidenced by X‐ray and microscopic analysis of the steel surface and the steel/cement paste interface

Investigation of Corrosion and Cathodic Protection in Reinforced Concrete

Effect of surface preparation on the evolution of the passive films formed on AISI 304L

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