Structure Analysis of Cation Selective Cr-goethite as Protective Rust of Weathering Steel

Konishi, Hiroyuki; Yamashita, Masato; Uchida, Hitoshi; Мizuki, J.

doi:10.2320/matertrans.46.337

Cited by 20 publications

(24 citation statements)

References 15 publications

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“…21) The fundamental shape of the observed spectra indicates that akaganéite is contained in the rust samples. Additionally, the shoulder peak on the main absorption edge reveals the presence of the other chlorides in the rust samples.…”

Section: àmentioning

confidence: 99%

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Characterization of Rust Layer Formed on Fe, Fe-Ni and Fe-Cr Alloys Exposed to Cl-Rich Environment by Cl and Fe K-Edge XANES Measurements

et al. 2005

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Chloride in atmosphere considerably reduces the corrosion resistance of conventional weathering steel containing a small amount of Cr. Ni is an effective anticorrosive element for improving the corrosion resistance of steel in a Cl-rich environment. In order to clarify the structure of the protective rust layer of weathering steel, Cl and Fe K-edge X-ray absorption near edge structure (XANES) spectra of atmospheric corrosion products (rust) formed on Fe, Fe-Ni and Fe-Cr alloys exposed to Cl-rich atmosphere were measured. The Fe K-XANES measurements enable the characterization of a mixture of iron oxides such as rust. The chemical composition of the rust was determined by performing pattern fitting of the measured spectra. All the rust is composed mainly of goethite, akaganéite, lepidocrocite and magnetite. Among these iron oxides, akaganéite in particular is the major component in the rust. Additionally, the amount of akaganéite in the rust of Fe-Ni alloy is much greater than that in rust of Fe-Cr alloy. Akaganéite is generally considered to facilitate the corrosion of steel, but our results indicate that akaganéite in the rust of Fe-Ni alloy is quantitatively different from that in rust of Fe-Cr alloy and does not facilitate the corrosion of steel. The shoulder peak observed in Cl K-XANES spectra reveals that the rust contains a chloride other than akaganéite. The energy of the shoulder peak does not correspond to that of any well-known chlorides. In the measured spectra, there is no proof that Cl, by combining with the alloying element, inhibits the alloying element from acting in corrosion resistance. The shoulder peak appears only when the content of the alloying element is lower than a certain value. This suggests that the generation of the unidentified chloride is related to the corrosion rate of steel.

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Section: àmentioning

confidence: 99%

“…The others and akaganéite were used in the Cl K-XANES study. In the previous Cl K-XANES study, 21) we observed the spectra of MgCl 2 (another major component of seawater), NaClO 2 (relatively stable chlorate), FeCl 3 , CrCl 3 and CrCl 3 Á6H 2 O (well-known metal chlorides).…”

Section: Sample Preparationmentioning

confidence: 99%

Characterization of Rust Layer Formed on Fe, Fe-Ni and Fe-Cr Alloys Exposed to Cl-Rich Environment by Cl and Fe K-Edge XANES Measurements

et al. 2005

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“…The effect of nickel on the structure of iron oxyhydroxides and oxides should be further studied, although some models of the effect of nickel on the rust formed by chloride ions were proposed. 20,21) …”

Section: Characterizations Of Particlesmentioning

confidence: 99%

“…Actually, the addition of nickel seems to influence the structure of rust formed on their surface and especially brings the formation of the protective rust layer in a Cl-rich environment. 20,21) In addition, it has been reported that the unit cell dimensions of -FeOOH change slightly by the addition of nickel. 22) However, the role of nickel in the transformation of GR2(SO 4 2À ) into the iron oxyhydroxides and oxides in SO 4 2À -environment is unclear.…”

Section: Introductionmentioning

confidence: 99%

Characteristic Behavior of Nickel Ions during Transformation of Green Rust to Ferric Oxyhydroxides in Aqueous Solution

et al. 2008

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X-ray diffraction, transmission electron microscopy, and X-ray absorption spectroscopy were used for characterizing the role of nickel in the transformation of Green Rrust 2(SO 4 2À ) (GR2). GR2(SO 4 2À ) was synthesized from the solution of ferric and ferrous sulfate and that of sodium hydroxide. The suspension containing GR2(SO 4 2À ) with and without nickel was oxidized by passing oxygen gas into the aqueous solution, in which GR2(SO 4 2À ) was transformed into ferric oxyhydroxides. The pH and oxidation reduction potential (ORP) values of the aqueous solution were monitored during the transformation of GR2(SO 4 2À ). In addition, the concentrations of iron and nickel in the solution during the transformation of GR2(SO 4 2À ) were analyzed by using inductively coupled plasma atomic emission spectroscopy. The reaction conditions of the GR2(SO 4 2À ) suspension were found to be strongly influenced by the addition of nickel. The reaction product goethite, which was transformed from GR2(SO 4 2À ), also appeared to be stabilized by the addition of nickel. These results indicate that the species of the solid particles formed in the solution are controlled by the addition of foreign elements.

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“…While there have been many analyses of rust on the steels in mild environments, [3][4][5][6][7][8][9][10] there are many problems that remain unclear regarding the basic mechanisms of the rust formation 11) and the effect of alloy elements [12][13][14] in saline environments. Therefore, in order to obtain the corrosion guidance for weathering steels that can be used in coastal environment, the thermodynamic stability of various rusts (Fe-X system) was investigated using a binary-phase potential-pH diagram.…”

Section: Introductionmentioning

confidence: 99%

Corrosion Behavior of Silicon-Bearing Steel in a Wet/Dry Environment Containing Chloride Ions

Nishimura

2007

Mater. Trans.

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The rust of Si-bearing steel was analyzed by EPMA, XRF, XPS and TEM, and the electrochemical behavior of the rusted steel was investigated by the electrochemical impedance spectroscopy (EIS) method after wet/dry cyclic corrosion test with chloride ions.The 2.0 mass% Si-bearing steel showed high corrosion resistance compared to carbon steel (SM) in the corrosion test. EPMA and XPS showed that Si existed as a intermediate oxidized state such as Si 2þ in the inner rust layer for Si-bearing steel. TEM showed that nano-scale complex oxides containing Si were formed in the inner rust of the Si-bearing steel.EIS measurement was taken to estimate the rust resistance (Rrust) and corrosion reaction one (Rt) of the rusted steel. It was found that Rrust and Rt of Si-bearing steel were much larger than those of SM after the rust formation. The corrosion of Si-bearing steel could be suppressed by the formation of the nano-scale complex oxide containing Si in inner rust layer to prevent the penetration of Cl ions.

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Structure Analysis of Cation Selective Cr-goethite as Protective Rust of Weathering Steel

Cited by 20 publications

References 15 publications

Characterization of Rust Layer Formed on Fe, Fe-Ni and Fe-Cr Alloys Exposed to Cl-Rich Environment by Cl and Fe K-Edge XANES Measurements

Characterization of Rust Layer Formed on Fe, Fe-Ni and Fe-Cr Alloys Exposed to Cl-Rich Environment by Cl and Fe K-Edge XANES Measurements

Characteristic Behavior of Nickel Ions during Transformation of Green Rust to Ferric Oxyhydroxides in Aqueous Solution

Corrosion Behavior of Silicon-Bearing Steel in a Wet/Dry Environment Containing Chloride Ions

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